In recent years, as environmental degradation has become more and more serious, the Chinese government has formulated a series of environmental policies and regulations aimed at improving environmental quality. Does environmental regulation significantly inhibit environmental pollution? Environmental regulation will not only directly affect environmental pollution but also have an indirect impact on environmental pollution. This paper uses Bayesian posterior probability, the optimal model structure selection method, based on join 112 kinds of spatial econometric model structure, and the panel data of 30 provinces in China from 2003 to 2016 to study the effects of environmental regulation on environmental pollution base on the industrial agglomeration mechanism of synergy effect. The research covers the national level and four regions, including the eastern, central, western, and northeastern regions of China. The research shows that: (1) environmental regulation at the national level and in the eastern, central and northeastern regions can significantly curb environmental pollution, but the environmental pollution in the western region shows a significant trend of enhancement. (2) Increased industrial agglomeration across China has significantly worsened environmental pollution. (3) Environmental regulation and industrial agglomeration form a significant synergy effect, which has a significant positive impact on environmental pollution in regions other than northeast China, and a significant negative impact on environmental pollution intensity in northeast China.