1, open Adobe Acrobat. Open the PDF file you want to compress, but the free version does not have this function;

2. Use the "Save As" function. Open the file menu, hover over Save As, a submenu will be expanded, and then select Simplified PDF. You can also select the "Reduced PDF" function from the Document menu.

3. Choose compatibility. If you choose a newer version, the file will be smaller, but it may not open on the old version of Acrobat.

4. Save multiple files. If you want to make the same settings for multiple files, click Apply to Multiple Documents so that you can add multiple documents. In the Output Options dialog box, optimize the settings of folders and file names.