As of January 2011, Qihoo claims that it was the second most popular web browser in China (after Internet Explorer), with 172 million monthly active users, 44.1% of Internet users in China. The true figure is much lower (in the 2-7% range) according to multiple independent sources.
This is in large part due to the software being very difficult to uninstall. Furthermore, whenever a user attempts to install another browser, a warning pop-up claims that the new browser is unsafe and should not be run.
All Chinese public and private Education institution's network administrators are required by Chinese law to use 360 antivirus on all workstations. The 360 browser comes with the 360 antivirus.
A local competitor is the Sogou High-Speed Browser (Chinese: 搜狗高速浏览器) by Sogou.com.