Taking China A-share companies from 2008 to 2022 as a research sample, the PSM-DID model in counter-factual analysis was used to evaluate the implementation effect of green credit policies from the perspective of the debt scale of heavily polluting enterprises, and further analyze the impact of enterprise heterogeneity. The results show that after the implementation of the Green Credit Guidelines in 2012, the debt scale of heavily polluting enterprises has been significantly suppressed, and the policy effect is obvious, but there is an imbalance, and the state-owned heavy polluting enterprises and heavy polluting enterprises in areas with low local authority debt are more strongly suppressed, and the policy effect is relatively better. Finally, enlightenment and suggestions are put forward according to the conclusion.