Taking the policy network approach, this chapter investigates three mechanisms – policy agenda, power concentration and heterogeneity dependence – underlying the evolution of inter-government agency relations in China. Operationally, the chapter adopts a social network analysis-based method to quantitatively study China’s innovation policy network. The findings show that the formal policy network for innovation has not only sustained through the intervention of policy agenda but also self-organized because of policy network’s nature of power concentration and heterogeneity dependence. The presence of such mixed mechanisms in the evolution of China’s innovation policy network differs from the findings from industrialized countries where self-organization plays a central role. The findings advance our theoretical understanding of the evolution of innovation policy network and have implications for policymaking in emerging economies.