Abstract: Starting from the angle of the intensity of environmental regulation being endogenous from the scale and quality of foreign investments, this paper analyzes the mechanism of FDI affecting the industrial environmental efficiency on the basis of the extended Copeland and Taylor model, then it constructs a simultaneous equation model and a panel threshold regression model to empirically test the mechanism and effects of the impacts of FDI scale and quality on industrial environmental efficiency. The findings show that:（1）the scale of foreign investment can restrain the improvement of industrial environmental efficiency through the industrial structure channels, but the scale and quality of foreign investment can both improve the industrial environmental efficiency through environmental technology and economic development paths;（2）the characteristics of foreign investment will directly affect the extent even the direction of the impact of FDI on the strength of China’s environmental regulation, the FDI scale will lead to the strengthening of the local environmental regulation because of the environmental pressure brought by the FDI scale, while the quality of FDI as a potential resource scrambled by local governments tends to weaken the local environmental regulations; （3）both the impacts of FDI quality and FDI scale on the industrial environmental efficiency have significant double threshold effect. When the strength of environmental regulation is lower or higher, the effect of FDI scale on the industrial environmental efficiency is negative, and the impact of FDI quality on the industrial environmental efficiency is not significant. When the strength of environmental regulation is moderate, the negative effect of FDI scale on the industrial environmental efficiency will be weakened, while FDI quality can produce a positive effect on the industrial environmental efficiency.

Key words: FDI quality; environmental regulation; environmental efficiency; simultaneous equations model