1, open the PPT file to which background music needs to be added, select the first slide, click the audio button in the media group under the Insert tab, and select the audio in the file from the drop-down list.

2. In the Insert Audio dialog box that appears, select the file to be inserted, and then click the Insert button.

3. After inserting the audio file, you can see a small speaker icon and a progress bar on the slide. Don't worry about this, the slides will disappear after the show.

4. Then, it is an important step to set the start option in the audio options group under the Play tab in the audio tools options group to automatic. So that the audio can be played automatically.

5. At this point, select the "Loop until it stops" check box on the right.

6. Make the PPT auto-play setting successful.