Abstract:

The implementation of environmental tax policy is of great significance to promote ecological environment protection and green development. However， some researchers have not reached a broad consensus on whether environmental tax policy can effectively and pragmatically solve environmental pollution problems. They assume that the actual situation of the implementation effect of environmental tax policy is not yet ideal， and emphasize that the continuous improvement of environmental tax policy can promote its implementation effect to return to the ideal situation proposed by Pigou. It is argued that existing studies have responded to the controversy by only addressing when and under what conditions environmental tax policy is effective. A more general question is whether， as a punitive tax， environmental tax policy tools can solve environmental pollution problems in the established economic ecosystem， achieving a combination effect of environmental benefits， social benefits， and economic benefits？ This crucial question is mainly answered.By introducing the cumulative stock of environmental pollution and the stock of environmental governance capital investment， and using the continuous time differential game model， the effect of environmental tax policy is studied， and the internal mechanism of environmental tax policy between environmental pollution governance and environmental protection capital investment is expounded. The results show that： （1） In a perfect economic ecosystem， the optimal environmental tax policy design is equal to the shadow price of the cumulative stock of unit pollutant emission. The optimal environmental tax is related to the pollutant emission coefficient， the level of capital investment in product production and pollution control， etc. （2） The environmental tax policy design has a complex impact on the economy ecosystem. In a short time， it will reduce the cumulative stock of environmental pollution first and then increase， resulting in limited environmental benefits. But in a long time， it will reduce the cumulative stock of environmental pollution and improve the stock level of environmental governance capital investment， exerting greater environmental benefits and economic benefits. （3） When the environmental tax policy is implemented stably for a long time and forms a forced mechanism for polluting enterprises， the comprehensive effect of its environmental， economic and social benefits can promote the high-quality development of the economic ecosystem.The research conclusion of this paper provides a scientific basis for decision-making departments to attach importance to the rigid and stable implementation of environmental tax policy tools. It can help to explain the differentiated reality of environmental tax policy effects in different periods and empirical results of different researchers. It also can reveal the policy functional effects of environmental tax in the specific context of considering cumulative quantity， promoting the development of the economy towards green and sustainable direction.

Key words: pollutant emission control, environmental taxes, policy effect, differential game