Abstract: Taking environmental cost as an entry point, this paper divides environmental cost into internal environmental cost and external environmental cost, analyzes the impact of environmental cost on corporate performance using panel data of Chinese A-share heavily polluting listed companies from 2016 to 2020, and further tests the intermediary role of social responsibility performance. The results show that the investment of total environmental cost, internal environmental cost, and external environmental cost can significantly improve enterprise performance; there is a significant positive correlation between total environmental cost, internal environmental cost, and corporate social responsibility performance; social responsibility performance plays a partial mediating role in the impact of total environmental cost and internal environmental cost on corporate performance; environmental cost that lag for one period can significantly improve corporate performance, while environmental cost that lag for two periods do not have a significant impact on corporate performance, and the impact gradually weakens.