Local governments are important actors in environmental governance, and their environmental protection expenditures not only depend on regional development concepts and development conditions, but are also affected by the competitive relationship between local governments and the supervision of higher-level governments and the public. Based on the online search of environmental keywords to evaluate the degree of public environmental concern, and taking the first round of central environmental protection inspection as the quasi-natural experiment, the spatial-difference-in-differences（SDID） model was used to analyze the samples of 30 provincial-level regions in China from 2012 to 2018. It is found that: the intensity of environmental protection expenditure of each local government （the proportion of environmental protection fiscal expenditure in the budget of general fiscal expenditure） has a positive spatial autocorrelation relationship, and the environmental protection expenditure behavior of local governments has a competitive effect of mutual imitation; the public environmental concern has a significant positive spatial correlation. The increase of the public environmental concern can not only promote the increase of the intensity of local government environmental protection expenditure, but also help the governments of neighboring regions with similar geographical location, pollution emission level and economic development level to increase the environmental protection expenditure intensity; the policy effect of central environmental supervision on improving the intensity of local government environmental protection expenditure is not significant, but the supervision pressure on the accountability of officials has a significant promoting effect on the intensity of local government environmental protection expenditure. Therefore, the coordination and interaction between central government, local government and the public should be strengthened in environmental governance, and the improvement of local government’s environmental behavior should be promoted through “top-down” superior assessment and supervision and “bottom-up” public demand and supervision. On one hand, it is necessary to pay attention to the environmental preference and social supervision of the public, and use its spatial spillover effect to play a leading role in the radiation of typical demonstration areas. On the other hand, it is necessary to further implement and improve the central environmental protection supervision system, and effectively promote the performance of local governments’ environmental protection responsibilities through the combination of strict accountability and effective incentives.