There are 195m internet users under the age of 25 in China

"The China Internet Network Information Center (CNNIC) issued its "2009 Report on the Behavior of China's Young Internet Users" in Beijing today, showing that as of the end of 2009, China had reached a total of 195 mln young internet users, up 16.8% from the previous year, accounting for 50.7% of all internet users in China. Internet penetration among youth reached 54.5%, and 74% of all young internet users accessed the internet via mobile phone, up 24.3% from the previous year.
Young internet users spent a weekly average of 16.5 hours online, 1.9 hours longer than in 2008.
Most marked was young internet users' use of entertainment services, with usage of online music (88.1%), online video (67%), online literature (47.1%) and online gaming (77.2%) all higher than that of overall internet users. Young internet users also used online communication tools at higher rates than overall internet users, including blogs (68.8%), instant messaging (77%), social networking sites (50.9%) and BBS (31.7%). 73.9% of young Chinese internet users used search engines. In general, young Chinese internet users were less active on commerce-related internet applications, with online shopping and payment used by 26.5% and 22.9% of users, respectively.
85.7% of university students and 69.3% of middle- and high-school students who went online did so via mobile phone. Overall, young internet users were relatively active in usage of most mobile internet applications: 87.3% of young mobile internet users used online chat services, 60.8% used mobile search, and 54.5% used mobile music.
CNNIC defines internet users as Chinese nationals over the age of 6 who have used the internet within the past half year. Young internet users refers to those under the age of 25."
Source - CNNIC "2009 Report on the Behavior of China's Young Internet Users", reported by Marbridge Consulting, 26th April 2010