State-owned equity participation,as an important form of mixed-ownership reform,serves as a crucial means to promote the high-quality development of private enterprises.Corporate adherence to ESG(Environmental,Social,and Governance)principles is a concrete action in pursuing high-quality development.Consequently,whether state-owned equity participation can exert its environmental,social,and governance effects and give incentive to private enterprises to improve their ESG performance has become a question worthy of in-depth exploration.Using data from A-share private listed compa-nies from 2009 to 2022,this study examines the impact of state-owned equity participation on corporate ESG performance.The findings reveal that state-owned equity participation significantly enhances the ESG performance of private enterprises.Further analysis of the mechanisms shows that state-owned equity participation primarily improves corporate ESG perfor-mance through internal governance and resource support mechanisms.Additionally,media coverage acts as a"megaphone"effect,significantly amplifying the positive impact of state-owned equity participation on corporate ESG performance.Hetero-geneity analysis indicates that the effect of state-owned equity participation in promoting ESG performance is more pro-nounced in high-pollution and highly competitive industries.The results of the study provide theoretical support for the strate-gic allocation of state-owned capital and offer empirical data for private enterprises to refine their ESG strategies.