I couldn't find the answer for a long time, so I did it myself. Come and answer. This reason may not be suitable for everyone and is for reference only.

The reason is probably that YY has its own virus, and then some anti-virus software or firewalls directly intercepted it.

I turned off the firewall of avast antivirus software (I changed it myself). At present, the PPT download of YY education template is normal.

Others and so on.

(ppt download path of YY: C:\Users\ user name \ appdata \ roaming \ duowan \ YY \ business \ education \ download.

If you turn on the channel and don't load PPT, check this folder. If there are only four pictures without size all the time, PPT has not been downloaded at all. )