In this paper, changchun changsheng vaccine event was used as an exogenous impact factor to study the investors' attitude towards corporate social responsibility (CSR) of listed companies in the pharmaceutical industry. According to the results of the study, the standardized mean cumulative excess return (CASAR) was significantly positive during the event window. According to multiple linear regression analysis, there was a significant negative correlation between CSR and CASAR. The event window is divided into pre-event and post-event, and there is no significant relationship before the event, but there is a significant negative correlation after the event. The study also made recommendations. First, governments and regulators should issue appropriate policies to improve corporate social responsibility activities, especially in the pharmaceutical sector. Second, government supervision is necessary and effective as the "night watchman" in the market economy.