diff --git a/packages/vant/src/text-ellipsis/TextEllipsis.tsx b/packages/vant/src/text-ellipsis/TextEllipsis.tsx
index 3ebe1be27..4d4ea69ed 100644
--- a/packages/vant/src/text-ellipsis/TextEllipsis.tsx
+++ b/packages/vant/src/text-ellipsis/TextEllipsis.tsx
@@ -2,6 +2,7 @@ import {
   ref,
   watch,
   computed,
+  onActivated,
   onMounted,
   defineComponent,
   type ExtractPropTypes,
@@ -42,6 +43,7 @@ export default defineComponent({
     const expanded = ref(false);
     const hasAction = ref(false);
     const root = ref<HTMLElement>();
+    let needRecalculate = false;
 
     const actionText = computed(() =>
       expanded.value ? props.collapseText : props.expandText,
@@ -53,29 +55,31 @@ export default defineComponent({
       return match ? Number(match[0]) : 0;
     };
 
+    const cloneContainer = () => {
+      if (!root.value || !root.value.isConnected) return;
+
+      const originStyle = window.getComputedStyle(root.value);
+      const container = document.createElement('div');
+      const styleNames: string[] = Array.prototype.slice.apply(originStyle);
+
+      styleNames.forEach((name) => {
+        container.style.setProperty(name, originStyle.getPropertyValue(name));
+      });
+
+      container.style.position = 'fixed';
+      container.style.zIndex = '-9999';
+      container.style.top = '-9999px';
+      container.style.height = 'auto';
+      container.style.minHeight = 'auto';
+      container.style.maxHeight = 'auto';
+
+      container.innerText = props.content;
+      document.body.appendChild(container);
+
+      return container;
+    };
+
     const calcEllipsised = () => {
-      const cloneContainer = () => {
-        if (!root.value) return;
-
-        const originStyle = window.getComputedStyle(root.value);
-        const container = document.createElement('div');
-        const styleNames: string[] = Array.prototype.slice.apply(originStyle);
-        styleNames.forEach((name) => {
-          container.style.setProperty(name, originStyle.getPropertyValue(name));
-        });
-
-        container.style.position = 'fixed';
-        container.style.zIndex = '-9999';
-        container.style.top = '-9999px';
-        container.style.height = 'auto';
-        container.style.minHeight = 'auto';
-        container.style.maxHeight = 'auto';
-
-        container.innerText = props.content;
-        document.body.appendChild(container);
-        return container;
-      };
-
       const calcEllipsisText = (
         container: HTMLDivElement,
         maxHeight: number,
@@ -168,7 +172,12 @@ export default defineComponent({
 
       // Calculate the interceptional text
       const container = cloneContainer();
-      if (!container) return;
+
+      if (!container) {
+        needRecalculate = true;
+        return;
+      }
+
       const { paddingBottom, paddingTop, lineHeight } = container.style;
       const maxHeight = Math.ceil(
         (Number(props.rows) + 0.5) * pxToNum(lineHeight) +
@@ -209,6 +218,13 @@ export default defineComponent({
 
     onMounted(calcEllipsised);
 
+    onActivated(() => {
+      if (needRecalculate) {
+        needRecalculate = false;
+        calcEllipsised();
+      }
+    });
+
     watch(
       [windowWidth, () => [props.content, props.rows, props.position]],
       calcEllipsised,
diff --git a/packages/vant/src/text-ellipsis/test/__snapshots__/index.spec.ts.snap b/packages/vant/src/text-ellipsis/test/__snapshots__/index.spec.tsx.snap
similarity index 100%
rename from packages/vant/src/text-ellipsis/test/__snapshots__/index.spec.ts.snap
rename to packages/vant/src/text-ellipsis/test/__snapshots__/index.spec.tsx.snap
diff --git a/packages/vant/src/text-ellipsis/test/index.spec.ts b/packages/vant/src/text-ellipsis/test/index.spec.tsx
similarity index 72%
rename from packages/vant/src/text-ellipsis/test/index.spec.ts
rename to packages/vant/src/text-ellipsis/test/index.spec.tsx
index f5f142079..4f2b049b0 100644
--- a/packages/vant/src/text-ellipsis/test/index.spec.ts
+++ b/packages/vant/src/text-ellipsis/test/index.spec.tsx
@@ -1,5 +1,5 @@
 import { mount } from '../../../test';
-import { nextTick } from 'vue';
+import { defineComponent, KeepAlive, nextTick } from 'vue';
 import TextEllipsis, { type TextEllipsisInstance } from '..';
 
 const originGetComputedStyle = window.getComputedStyle;
@@ -34,6 +34,7 @@ afterAll(() => {
 
 test('should render action slot correctly', async () => {
   const wrapper = mount(TextEllipsis, {
+    attachTo: document.body,
     props: {
       content,
     },
@@ -57,6 +58,7 @@ test('should render action slot correctly', async () => {
 
 test('should render content correctly', async () => {
   const wrapper = mount(TextEllipsis, {
+    attachTo: document.body,
     props: {
       content,
     },
@@ -68,6 +70,7 @@ test('should render content correctly', async () => {
 
 test('Expand and Collapse should be work', async () => {
   const wrapper = mount(TextEllipsis, {
+    attachTo: document.body,
     props: {
       content,
       expandText: 'expand',
@@ -83,6 +86,7 @@ test('Expand and Collapse should be work', async () => {
 
 test('should emit click event after Expand/Collapse is clicked', async () => {
   const wrapper = mount(TextEllipsis, {
+    attachTo: document.body,
     props: {
       content,
       expandText: 'expand',
@@ -102,6 +106,7 @@ test('text not exceeded', async () => {
 
   const shortContent = 'Vant is a component library';
   const wrapper = mount(TextEllipsis, {
+    attachTo: document.body,
     props: {
       content: shortContent,
       expandText: 'expand',
@@ -112,3 +117,45 @@ test('text not exceeded', async () => {
   await nextTick();
   expect(wrapper.text()).not.toMatch('...');
 });
+
+// https://github.com/vant-ui/vant/issues/12445
+test('should recalculate the ellipsis state when the component is activated', async () => {
+  vi.useFakeTimers();
+
+  const Comp = defineComponent({
+    data() {
+      return {
+        show: false,
+      };
+    },
+    beforeMount() {
+      setTimeout(() => {
+        this.show = true;
+      }, 1000);
+    },
+    render() {
+      return this.show ? <TextEllipsis content={content} /> : null;
+    },
+  });
+
+  const wrapper = mount(
+    {
+      data() {
+        return {
+          render: true,
+        };
+      },
+      render() {
+        return <KeepAlive>{this.render ? <Comp /> : null}</KeepAlive>;
+      },
+    },
+    { attachTo: document.body },
+  );
+
+  wrapper.setData({ render: false });
+  await vi.advanceTimersByTimeAsync(1000);
+  await wrapper.setData({ render: true });
+  expect(wrapper.text()).toMatch(content);
+
+  vi.useRealTimers();
+});