i am from pakistan.i want to visit my friend in yanbian,China.is that easy if he sends me invition?

Except for an invitation from your friend in yanbian, you also need photocopy of his identity documents such as passport, identity card or residence booklet, etc.

If you can get all the papers from him, and you yourself can provide all the required documetns for a China tourist visa, it will be easy for you to get the visa.