China is a member of the World Trade Organization. As such, it is supposed to be doing away with trade barriers. China became a member of the WTO in 2001 and has been reducing its trade barriers. However, many people continue to complain that China continues to restrict trade.
For the most part, China does not have tariffs or quotas or really overt trade barriers like that. However, it does continue to engage in practices that have the effect of limiting imports from other countries. China's government imposes policies that are not exactly trade barriers, but which make it difficult for companies from other countries to compete in China. Go here for a US government report on such policies.