Abstract: How the structural monetary policy affects green investment and environmental protection investment in a differentiated manner, thus playing a role in green transformation, is an important issue worth studying. Taking the event of the central bank expanding the scope of collateral for MLF as a quasi-natural experiment, this paper employ the DID model and the SBM-DEA-Tobit model to study the impact of structural monetary policy on enterprises’ green investment decisions, and then the difference of the impact of green investment and environmental protection investment on economic and environmental performance is compared to verify the green transformation effect of the policy. The findings indicate that the expansion policy can promote corporate green investment, reduce corporate environmental investment, and optimize the structure of corporate green investment; its impact mechanism is to alleviate financing constraints and increase managers’ optimistic expectations. Enterprises with different property rights, scale, and degree of marketization in their location have heterogeneity in the impact of policies. The coordination of environmental regulatory policies and the improvement of public environmental awareness are conducive to the effectiveness of the expansion policies. Environmental investment can improve environmental performance more quickly than green investment, while green investment can improve both environmental and economic performance over a longer period of time. The expansion policy can achieve the unity of environmental friendliness and economic development by changing the green investment strategy of enterprises, which verifies the Porter hypothesis. Therefore, the People’s Bank of China can use the framework of structural monetary policy collateral to guide enterprises to improve the green investment structure, promote high-quality economic development, and help the green development of the small and medium-sized enterprises.

Key words: green transformation, collateral expansion, medium-term lending facility, environmental investment, green investment