The game payoff matrix between government and enterprise is constructed, applying Quasi-Birth-Death Evolutionary Game Model to analyze the evolutionary equilibrium under different environmental tax level and the tax condition to achieve the synergy governance, and also analyzing the effect of system mutation rate and subject learning ability on the evolutionary equilibrium.The results show that there exist threshold effect of environmental tax on the synergy governance between government and enterprise in the evolutionary process of environment governance.And under different condition of the gap of strength of government supervision and the gap of strength of enterprise governance, the threshold effects of environmental tax are heterogeneous. Then the enhancement of system mutation rate and decrease of subject learning ability can weaken the stability of synergy equilibrium. At last, the policy suggestions to promote the synergy governance between government and enterprise are provided.