question: The outbreak of the COVID-19 epidemic has had an adverse effect on China's economy. This paper uses the event study method to test and measure the impact of the open market reverse repo (OMRR) operation on the Chinese stock market. The results show that the OMRR operation generates a positive daily abnormal return and a positive daily cumulative abnormal return on average for all stocks. The impact is larger for non-state-owned enterprise (non-SOE) firms than for SOE firms, stocks of non-Hubei provinces than those of the Hubei province, and for stocks of the information transmission and technology industry than those of other industries. We suggest that our government implement more prudent monetary policies and more proactive fiscal policies.