Purpose This 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/approach The 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. Findings It 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.