In the process of promotion, new energy vehicles are facing the problem of market failure, which is not conducive to the long-term healthy development of the new energy vehicle industry and will also lead to inefficient resource allocation. Therefore, in order to realize the rational allocation of resources and promote the orderly development of new energy automobile industry, the government needs to issue a series of incentive policies. The influence of incentive policy on the promotion and application of new energy vehicles from the perspectives of single policy effect, policy synergy effect and intermediary effect, and deeply studies the nonlinear relationship between incentive policy and the promotion and application of new energy vehicles was analyzed. According to the empirical results draws the following conclusions. Subsidy policy, charging infrastructure and government purchase can significantly promote the popularization and application of new energy vehicles. The greater the population, the higher the income level and the more serious the environmental pollution, the greater the popularization and application of new energy vehicles. There is an inverted U-shaped relationship between government purchase and the promotion and application of new energy vehicles. The R&D innovation ability of enterprises plays an intermediary role between the incentive policy and the promotion and application of new energy vehicles. There are regional differences in the implementation effect of subsidy policy. In the first batch of pilot cities, the effect of subsidy policy is no longer obvious, and even has a negative impact on the promotion and application of new energy vehicles. In the second batch of pilot cities, subsidy policy can still significantly promote the promotion and application of new energy vehicles. The subsidy policy can significantly promote the popularization and application of pure electric vehicles, but it has a negative effect on the popularization and application of plug-in hybrid vehicles and fuel cell vehicles. Finally, according to the research results provides relevant policy suggestions for promoting the popularization and application of new energy vehicles.