Abstract: Carbon emissions trading and carbon tax are the main market-oriented means to reduce carbon emissions. In this paper, the double differential spatial Durman model (SDM-DID) and the mediation effect test are used to test the emission reduction effect, spatial spillover effect and action path. It is found that there is a significant positive correlation between China's carbon emissions in space, and there are spatial characteristics of high-high emission and low-emission areas. The two carbon emission reduction policies still have significant emission reduction effects after considering the spatial correlation, among which carbon emission trading has a positive spatial spillover effect, the surrounding areas of the pilot provinces can achieve carbon emission reduction with the help of the policy dividends of the pilot provinces, while the spatial spillover effect of the "carbon tax" is negative, there is a "pollution paradise" phenomenon, carbon emission trading can achieve carbon emission reduction by promoting the low-carbon transformation of industrial structure and improving the energy structure, and the "carbon tax" can reduce carbon emissions by improving energy efficiency and improving energy consumption structure.

Keywords: carbon emissions trading; carbon tax; Spatial double difference; space overflow; Action path