Effectively carrying out social responsibility is a critical strategy for the sustainable development of enterprises. Under the influence of institutional isomorphism, the relationship between corporate social responsibility and performance will be affected by the level of the peer firm’s social responsibility and government subsidies. Based on institutional theory, this paper discusses the relationship between corporate social responsibility (CSR) and corporate performance, using relevant data from Chinese listed companies. The results show that there is an inverted U-shaped relationship between social responsibility and corporate performance; the peer firm’s CSR and government subsidies weaken the inverted U-shaped relationship between CSR and corporate performance. The results provide useful theoretical insights for the performance of CSR.