A friend of mine lived in china for about 2 years, here is what he had to say about steroids there.
"From what I know they are not obtained very easily BUT, I never looked for them and I don't know about pharmacies in Beijing. What I could tell you is that China is a huge counterfeit market so I would be especially careful when buying any sort of medicine, remedy, whatever....I was always skeptical of the quality, I heard some horror stories.
Another this is getting syringes? Not sure where you could get those or if you would want to draw that kind of attention to yourself? Again, the safety issue with syringes would be enough to keep me away from it. Not sure about the legal status.
Out of any Chinese city, Beijing would probably be the last place I would want to get into anything illegal, the central government is there and people are more sophisticated and aware of illegalities that foreigners might get into. Needless to say, a Chinese prison is one of the last places I would want to be...I imagine getting deported wouldn't be too pleasant either, not to mention having that on your record.
I'm sure they are around, there are some big chinese dudes, it would probably be best to make friends with some guys at a local gym who you can safely assume are on the juice try and learn more from them."
Hope that helps