A report from Chinese strategic advisory firm Stenvall Skoeld suggests that Apple has a 10 percent penetration rate in China with the highest levels of ownership found in urban centers like Beijing, Guandong and Shanghai. The lowest percentage of ownership was found in Tibet which had a 0.1 percent penetration rate.
The report also claims that, at the end of 2011, China was home to 21 million iPhones and iPad. The actual number may be higher as China Mobile, which does not carry the iPhone, says it has 15 million iPhone users on its network.
You can read the full report on Stenvall Skoeld's website.