As an important policy to deepen supply-side structural reform and promote high-quality economic development, the reform of China's state-owned enterprises (SOEs) is particularly important for the dissolution of the established serious overcapacity problem. By sorting out and analyzing the economic effects of SOE restructuring and the ways of overcapacity resolution, this paper finds that SOE restructuring can alleviate overcapacity, and the main mechanisms include improving total factor productivity, promoting enterprise technological innovation and reducing capital intensity. This paper provides micro-level evidence for the alleviation of overcapacity in China, which is important for the high-quality development of the Chinese economy.