The Shanghaiist posted on this a few months ago already, but I just came across these Chinese beatboxing videos and had to explore further.   

Shanghaiist describes the clip:

So a certain Liu Feng, a multi-talented video editor from Beijing working at W+K Shanghai, traveled up to northern China over CNY to discover the secret behind a popular web video featuring a Chinese beat-boxing virtuoso.

What he found is hinted at in the trailer above. Yanji, a city of just over 400,000 people located near the border to North Korea, is a virtual breeding ground for fledgling Chinese beat-boxers. Taking elements from popular Korean, Chinese and American culture, Yanji's b-boys and b-girls are carving out a style all their own.

Want more? Here's an excellent selection of Chinese beatboxing videos from Vietnamese video search engine Baamboo.com, including more from the Yanji performers.  And if you don't mind navigating in Chinese, check out bbox.cn.com, a Chinese beatboxing site and the online home of the Chinese Bbox Association (is it really an official association?!).  There you can find a BBS forum with posts such as "My new work," but it won't let you download anything unless you register.  Once you do, however, you can immediately access at least .wav audio files that are oddly, wonderfully intimate, such as this original piece by fannesmjj which I think should be called If Your Mother Only Knew.  From (I'm guessing) some Chinese teenager, with really good English, directly to your ears:

Download 76156968.wav

Download 75591457.wav

Wikipedia nods to kouji 口技 in its definition of beatboxing.  Kouji is a form of indigenous Chinese vocal percussion performing art, but is not related to the current hiphop style. It's more like old vaudeville vocal performances that tell a story, for instance, of a car crash or a train leaving the station, as in this clip:

A search for 口技 on Google video turns up more beatboxing than traditional kouji, so at least some Chinese are linking the terms.

Even Supergirl Li Yuchun beatboxes in this clip from one of her concerts.

Finally, you must see "Beatboxing in China Tee shop," where a foreign guy beatboxes for his Chinese friends as they drink tea in Xi'an.  I'll have to try that the next time I'm invited to sing for Chinese friends.