diff --git a/apps/oss/serializers/file.py b/apps/oss/serializers/file.py
index 0515d9df61f..4e5b7b1f7b2 100644
--- a/apps/oss/serializers/file.py
+++ b/apps/oss/serializers/file.py
@@ -123,7 +123,7 @@ def get(self, with_valid=True):
             # 对于非范围请求或其他类型文件，返回完整内容
             headers = {
                 'Content-Type': content_type,
-                'Content-Disposition': f'{"inline" if file_type == "pdf" else "attachment"}; filename={encoded_filename}'
+                'Content-Disposition': f'attachment; filename={encoded_filename}'
             }
             return HttpResponse(
                 file_bytes,
diff --git a/ui/env.d.ts b/ui/env.d.ts
index 9e940bf8210..78713959bb3 100644
--- a/ui/env.d.ts
+++ b/ui/env.d.ts
@@ -1,5 +1,6 @@
 /// <reference types="vite/client" />
 declare module 'katex'
+declare module 'pdfjs-dist/build/pdf.mjs'
 interface Window {
   sendMessage: ?((message: string, other_params_data: any) => void)
   chatUserProfile: ?(() => any)
diff --git a/ui/package.json b/ui/package.json
index cb468636f27..31da1f66da4 100644
--- a/ui/package.json
+++ b/ui/package.json
@@ -44,6 +44,7 @@
     "nanoid": "^5.1.5",
     "node-forge": "^1.3.1",
     "nprogress": "^0.2.0",
+    "pdfjs-dist": "^5.6.205",
     "pinia": "^3.0.1",
     "recorder-core": "^1.3.25011100",
     "sanitize-html": "^2.17.0",
diff --git a/ui/src/components/ai-chat/component/knowledge-source-component/ParagraphDocumentContent.vue b/ui/src/components/ai-chat/component/knowledge-source-component/ParagraphDocumentContent.vue
index ee87885d495..686f6712ed4 100644
--- a/ui/src/components/ai-chat/component/knowledge-source-component/ParagraphDocumentContent.vue
+++ b/ui/src/components/ai-chat/component/knowledge-source-component/ParagraphDocumentContent.vue
@@ -1,18 +1,406 @@
 <template>
-  <div style="width: 100%; height: calc(100vh - 57px)">
-    <embed v-if="is_pdf" style="width: 100%; height: 100%" :src="pdfSrc" />
+  <div ref="viewerRef" class="pdf-viewer">
+    <div class="pdf-stage" ref="stageRef">
+      <div class="pdf-actions">
+        <el-button size="small" type="primary" plain @click="toggleFullscreen">
+          <el-icon><FullScreen /></el-icon>
+          <span>{{ isFullscreen ? '退出全屏' : '全屏' }}</span>
+        </el-button>
+      </div>
+
+      <div ref="pagesRef" class="pdf-pages" :class="{ 'is-hidden': !!overlayText }"></div>
+
+      <div v-if="loading" class="pdf-overlay">
+        <el-icon class="is-loading"><Loading /></el-icon>
+        <span>PDF 加载中...</span>
+      </div>
+
+      <div v-else-if="overlayText" class="pdf-overlay" :class="{ 'pdf-overlay--error': !!error }">
+        <span>{{ overlayText }}</span>
+      </div>
+    </div>
   </div>
 </template>
 
 <script setup lang="ts">
-import { computed } from 'vue'
+import {
+  computed,
+  markRaw,
+  nextTick,
+  onBeforeUnmount,
+  onMounted,
+  ref,
+  shallowRef,
+  watch,
+} from 'vue'
+import { FullScreen, Loading } from '@element-plus/icons-vue'
+import * as pdfjsLib from 'pdfjs-dist/build/pdf.mjs'
+
+pdfjsLib.GlobalWorkerOptions.workerSrc = new URL(
+  'pdfjs-dist/build/pdf.worker.min.mjs',
+  import.meta.url,
+).toString()
+
+type PdfDocumentProxy = any
+type RenderTask = any
+type PdfLoadingTask = any
+
 const props = defineProps<{
   detail?: any
 }>()
-const is_pdf = computed(() => {
-  return props.detail?.meta?.source_file_id
-})
+
+const viewerRef = ref<HTMLDivElement | null>(null)
+const stageRef = ref<HTMLDivElement | null>(null)
+const pagesRef = ref<HTMLDivElement | null>(null)
+
+const loading = ref(false)
+const error = ref('')
+const isFullscreen = ref(false)
+
+const pdfDoc = shallowRef<PdfDocumentProxy | null>(null)
+const loadingTaskRef = shallowRef<PdfLoadingTask | null>(null)
+const renderTasks = shallowRef<RenderTask[]>([])
+const requestToken = ref(0)
+
+const isPdf = computed(() => !!props.detail?.meta?.source_file_id)
+
 const pdfSrc = computed(() => {
-  return `${window.MaxKB.prefix}/oss/file/${props.detail?.meta?.source_file_id}`
+  const fileId = props.detail?.meta?.source_file_id
+  return fileId ? `${window.MaxKB.prefix}/oss/file/${fileId}` : ''
+})
+
+const overlayText = computed(() => {
+  if (error.value) return error.value
+  if (!isPdf.value) return '暂无 PDF 预览'
+  return ''
+})
+
+function clearPages() {
+  if (pagesRef.value) {
+    pagesRef.value.innerHTML = ''
+  }
+}
+
+async function cancelRenderTasks() {
+  if (!renderTasks.value.length) return
+
+  for (const task of renderTasks.value) {
+    try {
+      task.cancel()
+    } catch {
+      //
+    }
+  }
+
+  renderTasks.value = []
+}
+
+async function destroyLoadingTask() {
+  if (!loadingTaskRef.value) return
+
+  try {
+    await loadingTaskRef.value.destroy()
+  } catch {
+    //
+  } finally {
+    loadingTaskRef.value = null
+  }
+}
+
+async function destroyPdfDoc() {
+  if (!pdfDoc.value) return
+
+  try {
+    await pdfDoc.value.destroy()
+  } catch {
+    //
+  } finally {
+    pdfDoc.value = null
+  }
+}
+
+function getAvailableWidth() {
+  if (!stageRef.value) return 0
+  const style = getComputedStyle(stageRef.value)
+  const paddingLeft = Number.parseFloat(style.paddingLeft || '0')
+  const paddingRight = Number.parseFloat(style.paddingRight || '0')
+  return stageRef.value.clientWidth - paddingLeft - paddingRight
+}
+
+async function renderAllPages() {
+  if (!pdfDoc.value || !pagesRef.value) return
+
+  const currentToken = requestToken.value
+  const container = pagesRef.value
+  clearPages()
+  renderTasks.value = []
+
+  const availableWidth = getAvailableWidth()
+
+  for (let pageNum = 1; pageNum <= pdfDoc.value.numPages; pageNum++) {
+    if (currentToken !== requestToken.value) return
+
+    const page = await pdfDoc.value.getPage(pageNum)
+    if (currentToken !== requestToken.value) return
+
+    const baseViewport = page.getViewport({ scale: 1 })
+    const fitScale =
+      availableWidth > 0 && baseViewport.width > 0
+        ? Math.min(3, Math.max(0.5, availableWidth / baseViewport.width))
+        : 1
+
+    const viewport = page.getViewport({ scale: fitScale })
+
+    const canvas = document.createElement('canvas')
+    canvas.className = 'pdf-canvas'
+
+    const context = canvas.getContext('2d')
+    if (!context) continue
+
+    const outputScale = window.devicePixelRatio || 1
+    canvas.width = Math.floor(viewport.width * outputScale)
+    canvas.height = Math.floor(viewport.height * outputScale)
+    canvas.style.width = `${Math.floor(viewport.width)}px`
+    canvas.style.height = `${Math.floor(viewport.height)}px`
+
+    context.setTransform(1, 0, 0, 1, 0, 0)
+    context.clearRect(0, 0, canvas.width, canvas.height)
+    context.setTransform(outputScale, 0, 0, outputScale, 0, 0)
+
+    container.appendChild(canvas)
+
+    const task = markRaw(
+      page.render({
+        canvasContext: context,
+        viewport,
+      }),
+    )
+
+    renderTasks.value = [...renderTasks.value, task]
+
+    try {
+      await task.promise
+    } catch (err: any) {
+      if (err?.name !== 'RenderingCancelledException') {
+        throw err
+      }
+    } finally {
+      renderTasks.value = renderTasks.value.filter((item) => item !== task)
+    }
+  }
+}
+
+async function loadPdf(url: string) {
+  const currentToken = ++requestToken.value
+  loading.value = true
+  error.value = ''
+
+  await cancelRenderTasks()
+  await destroyLoadingTask()
+  await destroyPdfDoc()
+  clearPages()
+
+  try {
+    const loadingTask = pdfjsLib.getDocument({
+      url,
+    })
+
+    loadingTaskRef.value = markRaw(loadingTask)
+    const doc = await loadingTask.promise
+
+    if (currentToken !== requestToken.value) {
+      await doc.destroy()
+      return
+    }
+
+    loadingTaskRef.value = null
+    pdfDoc.value = markRaw(doc)
+
+    await nextTick()
+    await renderAllPages()
+  } catch (err: any) {
+    console.error(err)
+    error.value = err?.message || 'PDF 加载失败'
+    clearPages()
+  } finally {
+    if (currentToken === requestToken.value) {
+      loading.value = false
+    }
+  }
+}
+
+async function handleResize() {
+  if (!pdfDoc.value || loading.value) return
+
+  const currentToken = ++requestToken.value
+  loading.value = true
+  error.value = ''
+
+  try {
+    await cancelRenderTasks()
+    if (currentToken !== requestToken.value) return
+    clearPages()
+    await nextTick()
+    await renderAllPages()
+  } catch (err: any) {
+    console.error(err)
+    error.value = err?.message || 'PDF 重绘失败'
+  } finally {
+    if (currentToken === requestToken.value) {
+      loading.value = false
+    }
+  }
+}
+
+async function toggleFullscreen() {
+  try {
+    if (!document.fullscreenElement) {
+      await viewerRef.value?.requestFullscreen()
+    } else {
+      await document.exitFullscreen()
+    }
+  } catch (err) {
+    console.error('toggle fullscreen failed:', err)
+  }
+}
+
+function syncFullscreenState() {
+  isFullscreen.value = document.fullscreenElement === viewerRef.value
+}
+
+async function onFullscreenChange() {
+  syncFullscreenState()
+  await nextTick()
+  await handleResize()
+}
+
+watch(
+  pdfSrc,
+  async (url) => {
+    await nextTick()
+
+    if (!isPdf.value || !url) {
+      error.value = ''
+      await cancelRenderTasks()
+      await destroyLoadingTask()
+      await destroyPdfDoc()
+      clearPages()
+      return
+    }
+
+    await loadPdf(url)
+  },
+  { immediate: true },
+)
+
+let resizeTimer: number | null = null
+
+function onWindowResize() {
+  if (resizeTimer) {
+    window.clearTimeout(resizeTimer)
+  }
+
+  resizeTimer = window.setTimeout(() => {
+    handleResize()
+  }, 200)
+}
+
+onMounted(() => {
+  document.addEventListener('fullscreenchange', onFullscreenChange)
+  window.addEventListener('resize', onWindowResize)
+})
+
+onBeforeUnmount(async () => {
+  if (resizeTimer) {
+    window.clearTimeout(resizeTimer)
+    resizeTimer = null
+  }
+
+  document.removeEventListener('fullscreenchange', onFullscreenChange)
+  window.removeEventListener('resize', onWindowResize)
+  requestToken.value++
+
+  await cancelRenderTasks()
+  await destroyLoadingTask()
+  await destroyPdfDoc()
+  clearPages()
 })
 </script>
+
+<style scoped>
+.pdf-viewer {
+  width: 100%;
+  height: calc(100vh - 57px);
+  background: #fff;
+}
+
+.pdf-viewer:fullscreen {
+  width: 100vw;
+  height: 100vh;
+  background: #fff;
+}
+
+.pdf-stage {
+  position: relative;
+  width: 100%;
+  height: 100%;
+  overflow: auto;
+  background: #fff;
+}
+
+.pdf-actions {
+  position: sticky;
+  top: 12px;
+  right: 12px;
+  z-index: 3;
+  display: flex;
+  justify-content: flex-end;
+  padding: 12px 12px 0 12px;
+  pointer-events: none;
+}
+
+.pdf-actions :deep(.el-button) {
+  pointer-events: auto;
+}
+
+.pdf-pages {
+  width: 100%;
+  min-height: 100%;
+}
+
+.pdf-pages.is-hidden {
+  visibility: hidden;
+}
+
+:deep(.pdf-canvas) {
+  display: block;
+  width: 100%;
+  max-width: 100%;
+  height: auto;
+  margin: 0 0 12px 0;
+  background: #fff;
+  box-shadow: none;
+  border-radius: 0;
+}
+
+:deep(.pdf-canvas:last-child) {
+  margin-bottom: 0;
+}
+
+.pdf-overlay {
+  position: absolute;
+  inset: 0;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 8px;
+  background: #fff;
+  color: var(--el-text-color-regular);
+  font-size: 14px;
+  z-index: 2;
+}
+
+.pdf-overlay--error {
+  color: var(--el-color-danger);
+}
+</style>