what's mean of big?

though my college has a rock climbing wall,i had never climbing it 

It's not huge, but there are people doing it. Depends what city your in, but there are plenty of indoor walls around and some decent climbers. Obviously nothing like what you'd find back  home, and no course setters. 

Oh, OK it's just I know that  it's super popular in the south like in Yangshuo or Getu becoming super popular so I wondered if there were any good rocks/routes nearer by.

I'm not sure about Beijing, but I would imagine there are places.  I've seen bouldering walls in some small cities so Beijing should have something I imagine.