In the context of high-quality development, in response to the new requirements of improving the innovation system, can environmental regulation promote the simultaneous improvement of the quantity and quality of green innovation of enterprises? Based on the enterprise level, an index was constructed in this study to describe the intensity of environmental regulation, and the impact of environmental regulation on the quantity and quality of green innovation and the heterogeneous characteristics of environmental regulation through the mediating role of innovation investment was examined. The results show that environmental regulation can significantly promote the quantity of green innovation of enterprises, but the impact on the quality of innovation is not statistically significant, and the conclusion is still valid after the endogenous treatment and robustness test. Enterprise R&D investment and government subsidies play a partial and complete mediating role in the relationship between environmental regulation and the quantity and quality of green innovation of enterprises, respectively. The heterogeneity analysis shows that environmental regulation can affect the number of green innovation in the central region, foreign-funded enterprises and large enterprises. The impact on the quality of green innovation is more pronounced in state-owned enterprises and large enterprises.