diff --git a/package.json b/package.json
index 06e73a7..c8abcf8 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "marklite",
-  "version": "0.3.4",
+  "version": "0.3.5",
   "description": "Lightweight Markdown Editor for Windows",
   "main": "./dist/main/index.js",
   "scripts": {
diff --git a/src/main/ipc-handlers.ts b/src/main/ipc-handlers.ts
index 21b52bd..5d1cfa6 100644
--- a/src/main/ipc-handlers.ts
+++ b/src/main/ipc-handlers.ts
@@ -197,15 +197,16 @@ export function registerIpcHandlers(
 
   // 标签切换
   ipcMain.handle(IPC_CHANNELS.TAB_SWITCHED, (_event: IpcMainInvokeEvent, filePath: string | null) => {
-    state.activeFilePath = filePath || null
-    if (filePath && !validatePath(filePath)) {
+    const normalizedPath = filePath || null
+    if (normalizedPath && !validatePath(normalizedPath)) {
       fileWatcher.stop()
       return
     }
-    fileWatcher.start(filePath || '')
+    state.activeFilePath = normalizedPath
+    fileWatcher.start(normalizedPath || '')
     const win = getMainWindow()
     if (win && !win.isDestroyed()) {
-      win.setTitle(filePath ? `MarkLite - ${basename(filePath)}` : 'MarkLite')
+      win.setTitle(normalizedPath ? `MarkLite - ${basename(normalizedPath)}` : 'MarkLite')
     }
   })
 
diff --git a/src/renderer/App.tsx b/src/renderer/App.tsx
index 407a63a..74ccc84 100644
--- a/src/renderer/App.tsx
+++ b/src/renderer/App.tsx
@@ -74,7 +74,7 @@ export function App() {
   const handleReloadModified = useCallback(async () => {
     if (!externallyModified?.filePath || !window.electronAPI) return
     const result = await window.electronAPI.readFile(externallyModified.filePath)
-    if (result.success && result.content) {
+    if (result.success && result.content !== undefined) {
       const tab = tabs.find(t => t.filePath === externallyModified.filePath)
       if (tab) { updateTabContent(tab.id, result.content); setModified(tab.id, false) }
     }
diff --git a/src/renderer/components/Sidebar/Sidebar.tsx b/src/renderer/components/Sidebar/Sidebar.tsx
index 6993401..3144867 100644
--- a/src/renderer/components/Sidebar/Sidebar.tsx
+++ b/src/renderer/components/Sidebar/Sidebar.tsx
@@ -9,7 +9,7 @@ import { useSidebarResize } from '../../hooks/useSidebarResize'
 import { useFolderOperations } from '../../hooks/useFolderOperations'
 import { useAutoExpandDir } from '../../hooks/useAutoExpandDir'
 import { OutlinePanel, parseHeadings } from '../OutlinePanel'
-import { getEditorView } from '../../stores/editorStore'
+import { getEditorView, useEditorStore } from '../../stores/editorStore'
 import { TextSelection } from '@milkdown/prose/state'
 
 const norm = (p: string) => p.replace(/\\/g, '/')
@@ -29,6 +29,7 @@ export const Sidebar = React.memo(function Sidebar() {
   const activeFilePath = activeTab?.filePath ?? null
   const { sidebarRef, startResize } = useSidebarResize()
   const { handleOpenFolder } = useFolderOperations()
+  const setLoading = useEditorStore(s => s.setLoading)
   useAutoExpandDir(activeFilePath)
 
   // Parse headings from active tab content
@@ -56,12 +57,17 @@ export const Sidebar = React.memo(function Sidebar() {
     const existing = tabs.find(t => t.filePath === path)
     if (existing) { switchToTab(existing.id); return }
     if (!window.electronAPI) return
-    const result = await window.electronAPI.readFile(path)
-    if (result.success && result.content) {
-      createTab(path, result.content)
-      recentFilesRepository.add(path)
+    setLoading('file-open', true)
+    try {
+      const result = await window.electronAPI.readFile(path)
+      if (result.success && result.content !== undefined) {
+        createTab(path, result.content)
+        recentFilesRepository.add(path)
+      }
+    } finally {
+      setLoading('file-open', false)
     }
-  }, [tabs, switchToTab, createTab])
+  }, [tabs, switchToTab, createTab, setLoading])
 
   const independentFiles = tabs.filter(t => {
     if (!t.filePath) return false
diff --git a/src/renderer/components/StatusBar/StatusBar.tsx b/src/renderer/components/StatusBar/StatusBar.tsx
index ee2bd4c..a6899fa 100644
--- a/src/renderer/components/StatusBar/StatusBar.tsx
+++ b/src/renderer/components/StatusBar/StatusBar.tsx
@@ -1,12 +1,14 @@
 import React from 'react'
 import { useTabStore } from '../../stores/tabStore'
 import { useEditorStore } from '../../stores/editorStore'
+import { useDocStats } from '../../hooks/useDocStats'
 import { getFileName } from '../../lib/fileUtils'
 import { LoadingSpinner } from '../LoadingSpinner/LoadingSpinner'
 
 export const StatusBar = React.memo(function StatusBar() {
   const activeTab = useTabStore(s => s.getActiveTab())
   const loadingStates = useEditorStore(s => s.loadingStates)
+  const stats = useDocStats(activeTab?.content)
 
   // 判断是否有任何加载状态激活
   const hasLoading = Object.values(loadingStates).some(Boolean)
@@ -32,6 +34,22 @@ export const StatusBar = React.memo(function StatusBar() {
         </span>
       </div>
       <div className="status-right">
+        {activeTab && (
+          <>
+            <span className="status-stat" title="行数" aria-label={`${stats.lines} 行`}>
+              {stats.lines} 行
+            </span>
+            <span className="status-divider">|</span>
+            <span className="status-stat" title="单词数" aria-label={`${stats.words} 个单词`}>
+              {stats.words} 词
+            </span>
+            <span className="status-divider">|</span>
+            <span className="status-stat" title="字符数（含空格）" aria-label={`${stats.chars} 个字符`}>
+              {stats.chars} 字符
+            </span>
+            <span className="status-divider">|</span>
+          </>
+        )}
         <span id="status-encoding">UTF-8</span>
         <span className="status-divider">|</span>
         <span id="status-lang">Markdown</span>
diff --git a/src/renderer/hooks/__tests__/useDocStats.test.ts b/src/renderer/hooks/__tests__/useDocStats.test.ts
new file mode 100644
index 0000000..20cd170
--- /dev/null
+++ b/src/renderer/hooks/__tests__/useDocStats.test.ts
@@ -0,0 +1,76 @@
+import { describe, it, expect } from 'vitest'
+import { computeDocStats } from '../useDocStats'
+
+describe('computeDocStats', () => {
+  it('should return zeros for undefined content', () => {
+    expect(computeDocStats(undefined)).toEqual({ words: 0, chars: 0, charsNoSpace: 0, lines: 0 })
+  })
+
+  it('should return zeros for null content', () => {
+    expect(computeDocStats(null)).toEqual({ words: 0, chars: 0, charsNoSpace: 0, lines: 0 })
+  })
+
+  it('should return zeros for empty string', () => {
+    expect(computeDocStats('')).toEqual({ words: 0, chars: 0, charsNoSpace: 0, lines: 0 })
+  })
+
+  it('should count single word', () => {
+    const result = computeDocStats('hello')
+    expect(result.words).toBe(1)
+    expect(result.chars).toBe(5)
+    expect(result.charsNoSpace).toBe(5)
+    expect(result.lines).toBe(1)
+  })
+
+  it('should count multiple words', () => {
+    const result = computeDocStats('hello world')
+    expect(result.words).toBe(2)
+    expect(result.chars).toBe(11) // 'hello world' = 11 chars
+    expect(result.charsNoSpace).toBe(10) // without the space
+  })
+
+  it('should count characters without spaces', () => {
+    const result = computeDocStats('a b c')
+    expect(result.chars).toBe(5)
+    expect(result.charsNoSpace).toBe(3)
+  })
+
+  it('should count lines', () => {
+    const result = computeDocStats('line1\nline2\nline3')
+    expect(result.lines).toBe(3)
+    expect(result.words).toBe(3)
+  })
+
+  it('should handle Windows line endings', () => {
+    const result = computeDocStats('line1\r\nline2\r\nline3')
+    expect(result.lines).toBe(3)
+  })
+
+  it('should handle trailing newline', () => {
+    const result = computeDocStats('hello\n')
+    expect(result.lines).toBe(2)
+    expect(result.words).toBe(1)
+  })
+
+  it('should count markdown content correctly', () => {
+    const md = '# Title\n\nThis is a **paragraph** with some *text*.\n\n- List item 1\n- List item 2\n'
+    const result = computeDocStats(md)
+    expect(result.words).toBe(17)
+    expect(result.lines).toBe(7)
+    expect(result.chars).toBe(md.length)
+  })
+
+  it('should handle whitespace-only content', () => {
+    const result = computeDocStats('   \n  \n  ')
+    expect(result.words).toBe(0)
+    expect(result.chars).toBe(9)
+    expect(result.charsNoSpace).toBe(0)
+    expect(result.lines).toBe(3)
+  })
+
+  it('should handle content with non-ASCII characters', () => {
+    const result = computeDocStats('中文测试 日本語 한국어')
+    expect(result.words).toBe(3)
+    expect(result.chars).toBe(12)
+  })
+})
diff --git a/src/renderer/hooks/useDocStats.ts b/src/renderer/hooks/useDocStats.ts
new file mode 100644
index 0000000..7bf1a8c
--- /dev/null
+++ b/src/renderer/hooks/useDocStats.ts
@@ -0,0 +1,39 @@
+import { useMemo } from 'react'
+
+export interface DocStats {
+  /** 单词数（按空白字符分割） */
+  words: number
+  /** 总字符数（含空白字符） */
+  chars: number
+  /** 字符数（不含空白字符） */
+  charsNoSpace: number
+  /** 行数 */
+  lines: number
+}
+
+/**
+ * 计算文档统计信息：单词数、字符数（含/不含空格）、行数。
+ * 对空文档或 undefined 返回全零值。
+ */
+export function computeDocStats(content: string | undefined | null): DocStats {
+  if (!content) {
+    return { words: 0, chars: 0, charsNoSpace: 0, lines: 0 }
+  }
+
+  const chars = content.length
+  const charsNoSpace = content.replace(/\s/g, '').length
+  const words = content.trim()
+    ? content.trim().split(/\s+/).length
+    : 0
+  const lines = content === '' ? 0 : content.split(/\r?\n/).length
+
+  return { words, chars, charsNoSpace, lines }
+}
+
+/**
+ *  Hook：根据文档内容实时计算统计信息。
+ *  使用 useMemo 避免不必要的重新计算。
+ */
+export function useDocStats(content: string | undefined | null): DocStats {
+  return useMemo(() => computeDocStats(content), [content])
+}
diff --git a/src/renderer/hooks/useFileOperations.ts b/src/renderer/hooks/useFileOperations.ts
index 9087329..c1daa27 100644
--- a/src/renderer/hooks/useFileOperations.ts
+++ b/src/renderer/hooks/useFileOperations.ts
@@ -70,7 +70,7 @@ export function useFileOperations(showToast: (msg: string, type?: ToastType) =>
     setLoading('file-open', true)
     try {
       const result = await window.electronAPI.readFile(filePath)
-      if (result.success) {
+      if (result.success && result.content !== undefined) {
         createTab(filePath, result.content)
         recentFilesRepository.add(filePath)
         setTimeout(() => useTabStore.getState().saveToDB(), 100)
diff --git a/src/renderer/styles/global.css b/src/renderer/styles/global.css
index 81c4782..f2eeb54 100644
--- a/src/renderer/styles/global.css
+++ b/src/renderer/styles/global.css
@@ -566,6 +566,10 @@ body {
   color: var(--border);
 }
 
+.status-stat {
+  white-space: nowrap;
+}
+
 /* Drop Overlay */
 #drop-overlay {
   position: fixed;