The paper takes listed companies in the heavily polluting industry from 2009-2017 as a research sample to explore whether heavy pollution enterprises' environmental protection investment helps their debt financing under the institutional background of China's continuous implementation of green credit policy. It is found that, in general, the environmental protection investment of heavy pollution enterprises helps them to obtain more and relatively long-term new loans; in terms of time, this effect is more evident after the release of China's Green Credit Guidelines in 2012; in addition, the level of regional environmental pollution, the level of financial development and the green fiscal policy also have a moderating effect on this. This paper enriches the study of the economic consequences of corporate environmental protection investment from the perspective of debt financing. It examines the effects of the implementation of China's green credit policy and other institutional factors to provide a reference for the heavy pollution enterprises' environmental protection investment and the implementation of green credit policy by local governments in China.