With the development of international diversification, China’s firms encounter severe challenges abroad. However, the research on the relationship between international diversification and performance of China’s firms has been underexplored. Using the 2002-2014 panel data of China’s listed manufacturing firms, we explore the effects of international diversification on performance of China’s firms, and examine the role of firm’s ownership. The results show that there is an inverted-M relationship between international diversification and performance; the performance of state-owned enterprises is significantly better than that of private firms during the process of international diversification.