The dual goals of green financial policies are to direct funds into green industries and promote the transformation of polluting enterprises. A difference-in-differences model was utilized to examine how the Green Credit Guidelines, introduced in 2012, affected the performance of polluting enterprises. Data from 968 non-financial listed companies on the A-share market in China between 2004 and 2017 were analyzed. The Green Credit Guidelines are found to reduce both the short-term and long-term performance of enterprises in heavily polluting industries. This negative impact is achieved through the channels of financing constraints, investment constraints, and internal control quality effects. After the implementation of the Green Credit Guidelines, the scale of investment by polluting enterprises in fixed assets, intangible assets, and other long-term assets decreases. The financing constraints of polluting enterprises measured by the SA index tighten. The management status of polluting enterprises measured by the internal control quality index deteriorates. Heterogeneity analysis shows that the Green Credit Guidelines has a more obvious impact on the performance of state-owned polluting enterprises and polluting enterprises in areas with low marketization and weak environmental regulation. Reliable evidence is provided on the impact of green credit on the economic performance of enterprises at the micro level, and policy insights are given on how green finance policies can aid in the green transformation of polluting enterprises