Sorry, this is a bit late, but I was in Beijing recently and was also trying to find a magic shop there.
I found the name of one on the Internet, figured out where it was, and got a taxi driver to take me there.... I believe it was supposed to be in a place called "Long Foo Plaza" if I remember correctly... anyways, when I got there, I saw that the whole "Long Foo Plaza" complex was shut down.
At the Silk Market in Beijing there is a small magic stand... but they mainly sell novelty and kids magic items... not a lot for serious magicians or pros. If you do find something there you like, be sure to bargain... they will quote you a really high price initially!