1. Click the file in the toolbar in the upper left corner of ppt and select "Save As" in the drop-down box.

2. There is a tool in the upper right corner of the Save As tab. Click Tools and select "Compress Pictures" in the drop-down box.

The second type

Use software. NXPowerLite is an excellent PowerPoint document compression tool. It can greatly reduce the size of your PowerPoint document, even reaching 50% ~ 70% of the original size.