PurposeThis study aims to deem the new policy – talk for environmental protection – promoted in the second half of 2014 to be the exogenous event and adopts PSM and DID to verify whether and how the central government’s mechanism of supervision of environmental enforcement improves firm environmental performance and reveals the micro effect and working mechanism of the supervision of environmental enforcement.Design/methodology/approachThe researchers first select reasonable control groups for target districts by means of PSM, then apply DID to compare corporations in the treatment group with those in the control group for the change of environmental performance before and after the talk for environmental protection, so as to evaluate the micro-level effect of such talks on corporate environmental performance; after that, the research examines the working mechanism of such talks on corporate environmental performance; then, it goes a step further to find out the environmental impact of such talks on corporations of different natures of property right.FindingsIt is found from the research that the talk for environmental protection will effectively improve the environmental performance of corporations in the target districts, and the improvement of environmental performance in state-owned corporations in the target districts will be more evident. However, such improvements, to a certain extent, are achieved by reducing the output value, and corporations do not increase environmental investments from a long-term perspective.Research limitations/implicationsFirst, the targets of the talk for environmental protection are mainly principals of municipal governments, but the research expands the scope to the whole province due to the small sample at the municipal level. Despite evidences showing that such a pressure of supervision impacts the whole province, the results obtained based on the data at the municipal level will be accurate. Second, the research selects a relatively short research period. Third, due to the limited data on corporate environmental performance in China, the research selects only listed companies from key monitored and controlled firms by state.Practical implicationsFirst, for the central government, environmental policy making is not the end of its job; it shall also supervise local governments’ work at environmental governance and properly handle its relationship with local governments. Second, for the local governments, in the course of implementing environmental policies, they should not only strengthen law enforcement but keep the continuity of law enforcement to avoid moving law enforcement. Third, in the long run, corporations must start from the source of production to enhance environmental governance and make cleaner production, so as to keep boosting corporate competitiveness and their ability of fighting risks.Originality/valueFirst, the research innovatively provides empirical evidence about the effect of China’s supervision of environmental enforcement. Previous studies on this topic are mostly theoretical discussions only, while this research makes the talk for environmental protection the exogenous event about the supervision of law enforcement and achieves breakthroughs in empirical studies of administrative enforcement supervision. Second, the research pushes the studies on the implementation effect of environmental policies from a medium level to a micro level. Third, the research achieves some breakthroughs in the data for measuring corporate environmental performance.