Abstract: Based on the reform practice of adjusting the environmental tax standard, this paper adopts the difference-in-difference method to investigate the heterogeneous effect of policy intervention, and discusses the impact of environmental protection tax on the green technology innovation. The results show that environmental tax has a significant positive effect on both the extensibility and intensiveness of green technology innovation, which supports "Porter Hypothesis". The environmental tax forces the green technology innovation for medium-sized and lager firms, but the impact on small firms is not significant. The effect of environmental tax adjustment policy on green technology innovation is more prominent for firms in high-polluting industries, in cities with strong policy execution and in regions with green tax policy. Environmental protection taxes will bring dividends to environmental governance, but supporting policies are needed to reduce the adverse impact on small and micro-enterprises.

Key words: environmental protection tax, green tax system, green total factor productivity, green technology innovation