songhuajiang I am afraid that people from China are (as far as we've heard) unable to access all forums, because our IP was possibly blocked too. The main site is behind a Cloudflare proxy, so it should be reachable by everyone.
Sanguine (owner of FreeFlarum) is currently on vacation, so we are unable to solve this issue as of right now. The only possible way to access a FreeFlarum forum from China is to use a proxy or VPN.
We cannot put all forums behind a proxy because that's only available in a paid Cloudflare plan. When Sanguine is back, he will probably change FreeFlarum's IP address to possibly bypass the ban. This will only work if the IP is banned, and not our domain. I thought I'd make this clear for some people. I apologize, but there's not much I can do to help you right now. I can try to look for a different captcha service, if it's supported by the library that we use at our webserver, but that's pretty much it