Driven by the strategy of innovation-driven development,Sthe policy interaction between local governments presents a new connotation and new characteristics of "competition for innovation". Based on the panel data of 258 prefecture-level cities from 2010 to 2019, this paper used the panel threshold model and spatial econometric model to investigate the local impact and spatial effect of local government innovation support policies. The results show that :(1) In terms of local effect, the impact of innovation support policy on local innovation level presents a significant inverted U-shaped relationship, and according to the current situation, policy incentives are generally effective. At the same time, the local effect of innovation policy increases with the expansion of local fiscal scale, showing a significant threshold characteristic. (2) In terms of spatial effect, this paper provides empirical evidence for regional innovation competition, and finds that the spatial effect of regional innovation competition also shows an inverted U-shaped feature of promotion at low intensity and inhibition at high intensity, but this spatial effect is not obvious in the central and western cities. (3) The heterogeneity test of innovation quality shows that regional innovation competition is more likely to stimulate low-level innovation activities, which aggravates the problem of emphasizing quantity over quality in regional innovation development. The research of this paper has important policy implications for promoting the formation of good innovation "competition-cooperation situation" between regions.