Over the last three decade, China's participation in the World Bank and IMF has undergone three stages: initial participation, steady development and partner stage. From recipient to contributor, from receiving technical assistance to sharing experience, from borrow loans to be co-donor, China has definitely engaged more in the international financial institutions and become a great player in international affairs. Why China has changed its attitude and behavior towards the World Bank and IMF and Will China reconstruct the international financial system? This thesis explore the answer from three international relations theories which are structural realism, neoliberal institutionalism, constructivism, to test the three hypotheses by analyzing the whole process of engagement among more than 30 years and two important cases. The first case is about voting power reform of the IMF and World Bank, which aroused wide attention around the world and China eagerly wants to gain more. The second case that China against the 2007 surveillance of IMF is to show the factual influence in decision-making process. The overview of China's engagement in the two organizations and the two cases fully test three hypotheses. This thesis argues that in the initial period, neoliberal institutionalism can better explained the interaction between China and World Bank and IMF. In recent century, China's proactive behavior can be better explained from structure realism and constructivism, which means that it is mainly due to the China's rising economic power and redefined identity and interest, But China will still behave in the system not to overthrow it. At the meantime, China probably will construct other institutions with area group to push the reform of international financial institutions. Keywords; China, international financial institutions, reform, voting power, decision-making.