China remains the largest manufacturing base in the world and is integral to the functioning of the international supply chain. Its future prosperity is directly linked with this role. Therefore it would not be in China's interest to allow a conflict that might jeopardise its industrial base.
Aside from manufacturing, China also has a burgeoning middle class who aspire to high living standards and a rich elite who enjoy the ability to invest their wealth abroad. The aspirations of both these influential groups within China are tied to the continuation of open markets between China and the rest of the world.