将多个 PDF 文件合并为一个——免费

Drop two or more PDFs onto the tool, drag the rows to set the merge order, and click Merge & Download. Pages from each source PDF are copied into a single output document in your chosen order. Your files are uploaded over HTTPS and merged with pdf-lib on our secure server, then automatically deleted afterward.

你可以对整个文件重新排序（上下拖动对应的行），也可以用垃圾桶图标将某个文件从合并中移除。如需对 PDF 内的单页重新排序，请先用我们的「整理 PDF」工具处理，然后再合并。

页面内容（文字、图片、字体、页面内的超链接）会被精确保留，因为 pdf-lib 是整体复制页面，而非重新渲染。由于新文件是一份全新文档，文档级书签和目录会被重置——如有需要，可用桌面端 PDF 编辑器重新添加书签。

Each file can be up to 50MB and you can merge up to 20 PDFs at once. In practice, merging a handful of large books (500+ pages each) or hundreds of small reports works comfortably within that limit.

Yes — your PDFs are uploaded over an encrypted (HTTPS) connection, merged with pdf-lib on our secure server, and automatically deleted afterward; we never store or share them. If your policy strictly forbids any upload at all (e.g. some compliance workflows for contracts, NDAs or medical records), use a desktop PDF tool that runs fully offline instead.

如果你知道密码，请先用我们的 PDF 密码工具解密，再进行合并。合并工具会在可能的情况下调用 ignoreEncryption，但采用严格加密（禁止打印/复制）的 PDF 需要先解锁。

会略小一些，因为合并过程中会对重复的字体和嵌入资源进行去重。差异通常只有几个百分点——只有在合并许多共用同一字体集的文件时（例如整套品牌报告系列）才比较明显。

免费使用，配有充裕的每日额度，输出不含水印，无需注册即可试用。每个文件最大可达 50MB，一次最多可合并 20 个 PDF。

是的 — 合并后的文件中每一页都保留自己的尺寸，因为 pdf-lib 是按原样复制页面，而非重新排版。一份 A4 合同、一张 Letter 尺寸的发票和一份横向表格可以全都放进同一个 PDF 中，各自保持原始尺寸。拖动各行即可控制哪份文档排在前面。

可以，但要用别的工具：「拆分 PDF」会把一段页码范围（如 5-12）提取为单独的文件，而「整理 PDF」可让你删除或重新排列合并后结果中的页面。合并只负责把文件拼到一起，所以当你需要再次把合并后的 PDF 拆开时，请使用这些配套工具。

Yes — click "Add more" at any time before merging; new files are appended to the end of the list with their own thumbnail rendered automatically. Drag them, or use the up/down arrow buttons, into position relative to the files already there — you don't need to restart the order from scratch.

Yes — every file row has small up/down arrow buttons next to the drag handle that move it one position at a time, which is far more reliable than a drag gesture on a touchscreen. Tap them repeatedly to walk a file to the top or bottom of the merge order.