Regional cooperative control policy is the key to improve the effectiveness of air pollution control in China. Firstly, the possible governance effects of policy implementation are analyzed, and hypotheses 1~4 are put forward. Furthermore, the industrial SO2 of prefecture-level cities and above was taken as the typical pollutant, and the difference-in-differences model (DID) was constructed to evaluate the emission reduction effect of regional collaborative governance policies, as well as the indirect impact of technological innovation, industrial structure and opening to the outside world. The results show that :(1). taking cities in the Beijing-Tianjin-Hebei region and the Yangtze river delta region as the experimental group, and other cities as the control group, the influence coefficient of regional collaborative governance policy is -1.3427, the policy significantly reduces the pollution emission level, and the model results are robust. (2). The sub-sample test shows that the policy effect of the Beijing-Tianjin-Hebei region is significantly better than that of the Yangtze River Delta region, and the policy effect of the economically developed region is higher than that of the less developed region. The regional heterogeneity in policy implementation cannot be ignored. (3) Among the three intermediary paths, regional collaborative governance policies have significant effect on pollution reduction through technological innovation and opening up, while the indirect driving effect through influencing industrial structure is weak. To further promote the implementation of regional collaborative governance policies, on the basis of full consideration of regional differentiation characteristics, attention should be paid to the identification of intermediary paths and the potential for emission reduction.