“The Middle East is China’s largest source of crude oil. Without it, the world’s second-largest economy would shudder to a halt. China has few economic interests in Syria itself but believes it has a strategic and diplomatic imperative to ensure Middle East stability and to protect a vital energy source. China effectively relies on a strong U.S. military presence in the region to guarantee stability and the smooth flow of oil, especially through the Strait of Hormuz, which Iran has threatened in the past to close in the event of war. That could increasingly grate on the Chinese and prompt a strategic re-think, said a diplomatic source who is familiar with China’s Middle East policy.”
http://www.reuters.com/article/2013/08/28/us-syria-crisis-china-analysis-idUSBRE97R08V20130828