Abstract: This paper studies the co-movement of global major stock markets by Nonlinear Granger causality test method which improved by Diks and Panchenko (2006) in the subprime mortgage crisis and the European debt crisis, and explores the problem of role of China’s stock market in the global risk contagion network of the two financial crises based on this. The results show that: (1) during the subprime mortgage crisis, China’s stock market was always the recipient of the risk, and played the role of risk-taking. During the European debt crisis, the role of risk-taking decreased significantly in China’s stock market and had risk overflow in some extent. In the global major stock markets’ risk contagion network of the two financial crises, the U.S. stock market is the only leader of global major stock markets. (2) By contrast two financial crises, the higher degree of risk contagion in the subprime mortgage crisis than the European debt crisis between the world's major stock markets. Rolling windows test could verify the robustness of the conclusion of this paper.