This study established its own greenwashing behavior indicators with reference to the KLD database and used regression analysis to explore the impact of ESG firms and greenwashing firms on cost of debt. The empirical results show that the impact of ESG firms on cost of debt is not significant, and the effect of greenwashing firms on cost of debt is also not significant. This empirical result means that when banks provide financing to firms, they do not obviously give firms better interest rates. This study not only fills the gap in the literature on greenwashing through the self-constructed greenwashing indicator but also provides a true picture of greenwashing among listed firms. In addition, authorities are reminded to pay more attention to the ESG performance of firms and curb the occurrence of greenwashing.