Under the background of “double carbon” goal, the “greenwashing” behavior of enterprises has been widely concerned by all sectors of society. Based on the data of listed companies in heavily polluting industries from 2013 to 2020, this paper empirically examines the impact and mechanism of disclosure of key audit matters on enterprises “greenwashing” behavior. It is found that the disclosure of key audit matters can significantly inhibit the “greenwashing” behavior of enterprises and improve the efficiency of green innovation. Mechanism analysis reveals that the disclosure of key audit matters mainly exerts its effect by reducing information asymmetr and gaining market trust, while simultaneously driving enterprises to fulfill their social responsibilities. Heterogeneity analysis shows that enterprises with lower environmental regulation intensity, negative tone of key audit matters, higher degree of digitization and lower level of risk bearing can enhance the policy effect of key audit matters disclosure. This paper has enriched the theoretical research on enterprise “greenwashing”, and expanded the analysis of the effect of environmental governance policies on the disclosure of key audit matters, so as to provide policy references for restraining “greenwashing” behavior and achieving a stable and efficient green transformation.