is there a way to find out all public ip assigned to China

I'm curious, why do you want to know? You could apply specific rules to China, or any other country, just by referring to the 2-letter country code.

You could use the geoip_lookup command on F5 to check to which country an IP belongs. https://support.f5.com/kb/en-us/solutions/public/15000/000/sol15042.html

As far as Im aware, without breaking the EULA and cracking the database at /usr/share/GeoIP/F5GeoIP.dat, you can not list all IPs belonging to a specific country. Information on such a scale can be used to create another GeoIP service to compete with Quova. Someone correct me if I'm wrong here.