diff --git a/README.md b/README.md
index 0e2bd32..ac89acd 100644
--- a/README.md
+++ b/README.md
@@ -28,3 +28,4 @@ English | [中文版本](./README-CN.md)
 - Select the conversations you wish to delete.
 - Click the "Bulk delete" button, and the selected conversations will be deleted.
 - If needed, you can click the "Remove checkboxes" button to hide the checkboxes.
+- It's possible to select all checkboxes between your last selection and the one being selected by holding shift.
diff --git a/addCheckboxes.js b/addCheckboxes.js
index aa21de1..42917d1 100644
--- a/addCheckboxes.js
+++ b/addCheckboxes.js
@@ -1,78 +1,152 @@
-console.log('addCheckboxes.js loaded');
-
-// Add checkboxes to each conversation
-function addCheckboxes() {
-    console.log('Adding checkboxes to conversations...', Selectors);
-    const conversations = document.querySelectorAll(Selectors.CONVERSATION_SELECTOR);
-
-    conversations.forEach((conversation, index) => {
-        let checkbox = conversation.querySelector(`.${CHECKBOX_CLASS}`);
-
-        // If the checkbox does not exist, create and insert it
-        if (!checkbox) {
-            checkbox = createCheckbox(index);
-            conversation.insertAdjacentElement('afterbegin', checkbox);
-        }
-
-        // Add click event to the conversation title
-        const titleElement = conversation.querySelector(Selectors.TITLE_SELECTOR);
-        if (titleElement) {
-            titleElement.style.cursor = 'default';
-
-            // Add click event listener if not already added
-            if (!titleElement.dataset.hasClickListener) {
-                addClickEventListener(titleElement);
-            }
-
-            // Add click event listener to the parent element if not already added
-            const parentElement = titleElement.parentElement;
-            if (parentElement && !parentElement.dataset.hasClickListener) {
-                parentElement.style.cursor = 'default';
-                addClickEventListener(parentElement);
-            }
-        }
-    });
-}
+console.log("addCheckboxes.js loaded");
 
 // Create a new checkbox element
 function createCheckbox(index) {
-    const checkbox = document.createElement('input');
-    checkbox.type = 'checkbox';
-    checkbox.className = CHECKBOX_CLASS;
-    checkbox.dataset.index = index;
-    checkbox.addEventListener('click', preventEventPropagation);
-    return checkbox;
+  const checkbox = document.createElement("input");
+  checkbox.type = "checkbox";
+  checkbox.className = CHECKBOX_CLASS;
+  checkbox.dataset.index = index;
+  checkbox.addEventListener("click", preventEventPropagation);
+  return checkbox;
 }
 
 // Add click event listener to an element
 function addClickEventListener(element) {
-    const handleTitleClick = (event) => {
-        toggleCheckbox(event);
-        event.stopPropagation();
-    };
-    element.addEventListener('click', handleTitleClick);
-    element.dataset.hasClickListener = 'true';
+  const handleTitleClick = (event) => {
+    toggleCheckbox(event);
+    event.stopPropagation();
+  };
+  element.addEventListener("click", handleTitleClick);
+  element.dataset.hasClickListener = "true";
 }
 
 function findAncestorWithCheckbox(el, selector) {
-    while ((el = el.parentElement) && !el.querySelector(selector));
-    return el;
+  while ((el = el.parentElement) && !el.querySelector(selector));
+  return el;
 }
 
 // Toggle the checkbox's checked state
 function toggleCheckbox(event) {
-    event.preventDefault();
-    event.stopPropagation();
+  event.preventDefault();
+  event.stopPropagation();
 
-    const parentElement = findAncestorWithCheckbox(event.currentTarget, `.${CHECKBOX_CLASS}`);
-    const checkbox = parentElement ? parentElement.querySelector(`.${CHECKBOX_CLASS}`) : null;
-    if (checkbox) {
-        checkbox.checked = !checkbox.checked;
+  const parentElement = findAncestorWithCheckbox(
+    event.currentTarget,
+    `.${CHECKBOX_CLASS}`
+  );
+  const checkbox = parentElement
+    ? parentElement.querySelector(`.${CHECKBOX_CLASS}`)
+    : null;
+  if (checkbox) {
+    checkbox.checked = !checkbox.checked;
+    checkPreviousCheckboxes(checkbox);
+
+    // 更新最后选中的复选框
+    if (checkbox.checked) {
+      window.lastCheckedCheckbox = checkbox;
     }
+  }
 }
 
-function preventEventPropagation(event) {
-    event.stopPropagation();
+function handleCheckboxClick(event) {
+  event.stopPropagation();
+
+  const clickedCheckbox = event.target;
+  checkPreviousCheckboxes(clickedCheckbox);
+
+  // 更新最后选中的复选框
+  window.lastCheckedCheckbox = clickedCheckbox;
 }
 
+function checkPreviousCheckboxes(clickedCheckbox) {
+  if (window.shiftPressed && window.lastCheckedCheckbox) {
+    const allCheckboxes = Array.from(
+      document.querySelectorAll(`.${CHECKBOX_CLASS}`)
+    );
+    const start = allCheckboxes.indexOf(window.lastCheckedCheckbox);
+    const end = allCheckboxes.indexOf(clickedCheckbox);
+
+    const [lower, upper] = start < end ? [start, end] : [end, start];
+
+    for (let i = lower; i <= upper; i++) {
+      allCheckboxes[i].checked = true;
+    }
+  }
+}
+
+function addShiftKeyEventListeners() {
+  console.log("Adding Shift key event listeners...");
+  document.addEventListener("keydown", (event) => {
+    if (event.key === "Shift") {
+      console.log("Shift key pressed");
+      window.shiftPressed = true;
+    }
+  });
+
+  document.addEventListener("keyup", (event) => {
+    if (event.key === "Shift") {
+      console.log("Shift key released");
+      window.shiftPressed = false;
+    }
+  });
+}
+
+// 添加复选框到每个对话
+function addCheckboxes() {
+  console.log("Adding checkboxes to conversations...", Selectors);
+  const conversations = document.querySelectorAll(
+    Selectors.CONVERSATION_SELECTOR
+  );
+
+  conversations.forEach((conversation, index) => {
+    let existingCheckbox = conversation.querySelector(`.${CHECKBOX_CLASS}`);
+
+    // 如果复选框已存在，获取其选中状态并移除它
+    let isChecked = existingCheckbox ? existingCheckbox.checked : false;
+    if (existingCheckbox) {
+      existingCheckbox.remove();
+    }
+
+    // 创建新的复选框并设置其属性
+    const checkbox = document.createElement("input");
+    checkbox.type = "checkbox";
+    checkbox.className = CHECKBOX_CLASS;
+    checkbox.dataset.index = index;
+    checkbox.checked = isChecked;
+    checkbox.addEventListener("click", handleCheckboxClick);
+    conversation.insertAdjacentElement("afterbegin", checkbox);
+
+    // add click event listener to the title element
+    const titleElement = conversation.querySelector(Selectors.TITLE_SELECTOR);
+    if (titleElement) {
+      titleElement.style.cursor = "default";
+
+      // get the parent element of titleElement
+      const parentElement = titleElement.parentElement;
+
+      // define a common event handler
+      const handleTitleClick = (event) => {
+        toggleCheckbox(event);
+        event.stopPropagation(); // prevent event propagation
+      };
+
+      // add click event listener to titleElement
+      if (!titleElement.dataset.hasClickListener) {
+        titleElement.addEventListener("click", handleTitleClick);
+        titleElement.dataset.hasClickListener = "true";
+      }
+
+      // add click event listener to the parent element of titleElement
+      if (parentElement && !parentElement.dataset.hasClickListener) {
+        parentElement.style.cursor = "default";
+        parentElement.addEventListener("click", handleTitleClick);
+        parentElement.dataset.hasClickListener = "true";
+      }
+    }
+  });
+
+  addShiftKeyEventListeners();
+}
+
+// run the main function
 addCheckboxes();
diff --git a/globals.js b/globals.js
index f2c50a8..d67a454 100644
--- a/globals.js
+++ b/globals.js
@@ -3,8 +3,6 @@ if (typeof window.globalsLoaded === "undefined") {
 
   window.globalsLoaded = true;
 
-  const lastChecked = null;
-
   const Selectors = {
     conversationsCheckbox: ".conversation-checkbox:checked",
     confirmDeleteButton: "button.btn.btn-danger",
@@ -32,8 +30,9 @@ if (typeof window.globalsLoaded === "undefined") {
   }
 
   // Expose variables to the global scope
-  window.lastChecked = lastChecked;
   window.Selectors = Selectors;
+  window.shiftPressed = false;
+  window.lastCheckedCheckbox = null;
   window.CHECKBOX_CLASS = CHECKBOX_CLASS;
 } else {
   console.log("globals.js already loaded, skipping re-initialization");
diff --git a/popup.css b/popup.css
index 6400c94..593895e 100644
--- a/popup.css
+++ b/popup.css
@@ -249,3 +249,98 @@ button#bulk-archive {
 #modalCancel:hover {
   background-color: #e2e6ea;
 }
+
+/* 调整 button-container 样式 */
+.button-container {
+  position: relative;
+  display: inline-block;
+  width: calc(50% - 5px); /* 调整宽度以适应两个按钮并留有间隙 */
+}
+
+/* 调整 tooltip-trigger 样式 */
+.tooltip-trigger {
+  position: absolute;
+  top: 5px;
+  right: 5px;
+  width: 16px;
+  height: 16px;
+  color: rgba(255, 255, 255, 0.9); /* 近白色 */
+  font-size: 14px;
+  font-style: italic;
+  font-weight: bold;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  cursor: help;
+  transition: all 0.3s ease;
+  z-index: 2;
+  text-shadow: 0 0 2px rgba(0, 0, 0, 0.5); /* 添加轻微阴影以增加可见度 */
+}
+
+/* 调整 tooltip-content 样式 */
+.tooltip-content {
+  visibility: hidden;
+  width: 130px;
+  background-color: #333;
+  color: #fff;
+  text-align: left;
+  border-radius: 6px;
+  padding: 10px;
+  position: absolute;
+  z-index: 3;
+  top: -5px;
+  left: calc(100% + 10px);
+  opacity: 0;
+  transition: opacity 0.3s, visibility 0.3s;
+  pointer-events: none;
+  font-style: normal;
+  font-weight: normal;
+  font-size: 12px;
+  line-height: 1.4;
+  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
+}
+
+.tooltip-content::after {
+  content: "";
+  position: absolute;
+  top: 10px;
+  right: 100%;
+  margin-top: -5px;
+  border-width: 5px;
+  border-style: solid;
+  border-color: transparent #333 transparent transparent;
+}
+
+.tooltip-trigger:hover .tooltip-content {
+  visibility: visible;
+  opacity: 1;
+}
+
+/* 确保按钮容器不会因为tooltip内容而变形 */
+.button-container {
+  position: relative;
+  display: inline-block;
+  width: calc(50% - 5px);
+  overflow: visible;
+}
+
+/* 可能需要调整按钮样式以适应新的布局 */
+.buttons-row button,
+.button-container button {
+  width: 100%;
+  height: 100%;
+  position: relative;
+  z-index: 1;
+}
+
+/* 更新按钮悬停效果 */
+.button-container:hover button,
+.button-container:hover .tooltip-trigger {
+  transform: translateY(-3px);
+}
+
+/* 添加悬停效果到 i 图标 */
+.tooltip-trigger:hover {
+  color: #fff; /* 完全白色 */
+  text-shadow: 0 0 4px rgba(255, 255, 255, 0.5); /* 增强悬停时的光晕效果 */
+}
diff --git a/popup.html b/popup.html
index 9b3f271..1496a1f 100644
--- a/popup.html
+++ b/popup.html
@@ -12,9 +12,17 @@
     </div>
     <div class="buttons-wrapper">
       <div class="buttons-row">
-        <button id="add-checkboxes">
-          <span>Add</span><br /><span>Checkboxes</span>
-        </button>
+        <div class="button-container">
+          <button id="add-checkboxes">
+            <span>Add</span><br /><span>Checkboxes</span>
+          </button>
+          <span class="tooltip-trigger" aria-label="information"
+            >i
+            <span class="tooltip-content"
+              >Hold Shift to select </br> multiple conversations.</span
+            >
+          </span>
+        </div>
         <button id="remove-checkboxes">
           <span>Remove</span><br /><span>Checkboxes</span>
         </button>