Comment system I chose valine,but many times I am not satisfied with the default avatar of valine.So I found something related on the Internet and successfully implemented this.
This is easy to achieve.
First: you shoule go to Gravatar to register an account.
Attention:The email you use when registering is important and will be used next.After the registration is completed, change the personal information and change the avatar you want to use.
Second: Fill in the email address when you comment, it will automatically match your avatar

Then you can find your avatar replaced with your own custom.

A common problem:
You may not received verification email when you are registering.
Reason: Some mailboxes have added gravatar to the blacklist.
Solution: Add the following address to your email address whitelist in your mailbox settings

donotreply@gravatar.com
donotreply@wordpress.com
support@gravatar.com

Such as QQ-mail


Then you should be able to find the verification email in the trash in the email.