diff --git a/web/app/components/base/markdown-blocks/__tests__/link.spec.tsx b/web/app/components/base/markdown-blocks/__tests__/link.spec.tsx
index 686ed236e8a..fb73fc38704 100644
--- a/web/app/components/base/markdown-blocks/__tests__/link.spec.tsx
+++ b/web/app/components/base/markdown-blocks/__tests__/link.spec.tsx
@@ -170,6 +170,57 @@ describe('Link component', () => {
     expect(link).toHaveAttribute('rel', 'noopener noreferrer')
   })
 
+  it('adds attachment mode to file-preview links by default', () => {
+    mockIsValidUrl.mockReturnValue(true)
+
+    const node = {
+      properties: {
+        href: 'http://localhost:5001/files/123/file-preview?timestamp=1&nonce=2&sign=3',
+      },
+    }
+
+    render(<Link node={node}>doc.pdf</Link>)
+
+    expect(screen.getByText('doc.pdf')).toHaveAttribute(
+      'href',
+      'http://localhost:5001/files/123/file-preview?timestamp=1&nonce=2&sign=3&as_attachment=true',
+    )
+  })
+
+  it('does not duplicate attachment mode for file-preview links', () => {
+    mockIsValidUrl.mockReturnValue(true)
+
+    const node = {
+      properties: {
+        href: 'http://localhost:5001/files/123/file-preview?timestamp=1&nonce=2&sign=3&as_attachment=true',
+      },
+    }
+
+    render(<Link node={node}>doc.pdf</Link>)
+
+    expect(screen.getByText('doc.pdf')).toHaveAttribute(
+      'href',
+      'http://localhost:5001/files/123/file-preview?timestamp=1&nonce=2&sign=3&as_attachment=true',
+    )
+  })
+
+  it('keeps protocol-relative file-preview links protocol-relative', () => {
+    mockIsValidUrl.mockReturnValue(true)
+
+    const node = {
+      properties: {
+        href: '//localhost:5001/files/123/file-preview?timestamp=1#page',
+      },
+    }
+
+    render(<Link node={node}>doc.pdf</Link>)
+
+    expect(screen.getByText('doc.pdf')).toHaveAttribute(
+      'href',
+      '//localhost:5001/files/123/file-preview?timestamp=1&as_attachment=true#page',
+    )
+  })
+
   // --------------------------
   // NO HREF
   // --------------------------
diff --git a/web/app/components/base/markdown-blocks/link.tsx b/web/app/components/base/markdown-blocks/link.tsx
index d9fab217d4b..cf7bdf6c08c 100644
--- a/web/app/components/base/markdown-blocks/link.tsx
+++ b/web/app/components/base/markdown-blocks/link.tsx
@@ -7,6 +7,19 @@ import * as React from 'react'
 import { useChatContext } from '@/app/components/base/chat/chat/context'
 import { isValidUrl } from './utils'
 
+const filePreviewPathPattern = /\/files\/[^/?#]+\/file-preview(?:[?#]|$)/
+const asAttachmentParamPattern = /[?&]as_attachment=/
+
+const withFilePreviewAttachment = (href: string) => {
+  if (!filePreviewPathPattern.test(href) || asAttachmentParamPattern.test(href))
+    return href
+
+  const url = new URL(href, 'http://dify.local')
+  url.searchParams.set('as_attachment', 'true')
+
+  return href.startsWith('//') ? url.href.replace(url.protocol, '') : url.href
+}
+
 const Link = ({ node, children, ...props }: any) => {
   const { onSend } = useChatContext()
   const commonClassName = 'cursor-pointer underline decoration-primary-700! decoration-dashed'
@@ -16,8 +29,9 @@ const Link = ({ node, children, ...props }: any) => {
     return <abbr className={commonClassName} onClick={() => onSend?.(hidden_text)} title={node.children[0]?.value || ''}>{node.children[0]?.value || ''}</abbr>
   }
   else {
-    const href = props.href || node.properties?.href
-    if (href && /^#[\w-]+$/.test(href.toString())) {
+    const rawHref = props.href || node.properties?.href
+    const href = rawHref?.toString()
+    if (href && /^#[\w-]+$/.test(href)) {
       const handleClick = (e: React.MouseEvent<HTMLAnchorElement>) => {
         e.preventDefault()
         // scroll to target element if exists within the answer container
@@ -36,7 +50,7 @@ const Link = ({ node, children, ...props }: any) => {
     if (!href || !isValidUrl(href))
       return <span>{children}</span>
 
-    return <a href={href} target="_blank" rel="noopener noreferrer" className={commonClassName}>{children || 'Download'}</a>
+    return <a href={withFilePreviewAttachment(href)} target="_blank" rel="noopener noreferrer" className={commonClassName}>{children || 'Download'}</a>
   }
 }