Overcapacity has become a "stubborn disease" in China's economic development. Empirical analysis is carried out to investigate and test the mechanism and mechanism of government fiscal intervention affecting investment and thus overcapacity. It is pointed out how to correctly use econometric model to analyze real economic problems, so as to obtain stable, reasonable and reliable parameter estimates, and then provide important reference for policy analysis. The research shows that promoting institutional reform and focusing on solving the fundamental drawbacks of the system are the basic requirements of "capacity reduction"; Taking enterprise independent innovation and human capital cultivation as the key, promoting the upgrading of industrial structure is the long-term strategy of "capacity reduction". Expanding consumer demand and accelerating the transformation of economic development mode are the only way to "reduce overcapacity".