Using China Model of TREMOVE and China national data, this paper simulates the implementation of new vehicle and vessel tax and carbon tax. The simulation results show that the implementation of new vehicle and vessel tax and carbon tax will make CO2 emissions decline 119 million tones in 2030. While if substitution of public traffic for private traffic is more elastic or the number of cars is limited, the declination of CO2 emissions will be more prominent. The combined implementation of both tax policies will make a positive effect on social welfare and government tax revenue. Under the double dividend effect, the positive effect on social welfare will be more significant by replacing service tax with environmental tax.