This study examines the impact of environmental protection fee reform tax on corporate greenwashing in heavily polluting enterprises in China. The findings indicate: The environmental protection fee reform tax significantly suppresses corporate greenwashing behavior. This effect is particularly pronounced in a poor market institutional environment, highly competitive industries, and private enterprises. The environmental protection fee reform tax primarily influences corporate greenwashing behavior by strengthening law enforcement norms and altering the incentives and risks associated with greenwashing. The findings of this paper are of great theoretical and practical significance for the comprehensive understanding of the micro-value effect of environmental protection fee-to-tax conversion and the promotion of policy optimization.