This paper developed a China energy-economic-environmental policy model based on a dynamic CGE model，designed a carbon tax scenario，a cap-and-trade scenario and a policy mix scenario，and simulated the economic and mitigation effects under different scenarios． The results show that only carbon tax policy cannot realize the 2020 mitigation target． Only cap-and-trade will cause high mitigation costs and tremendous mitigation pressure to regulated sectors． Combination of cap-and-trade with a low carbon tax can realize the 2020 mitigation target with modest mitigation costs and mitigation pressures for regulated sectors． Meanwhile， the dispersed emitter will also bear mitigation commitments at a certain extent． The results of this paper suggest a mixed policy combining cap-and-trade with a low carbon tax as the first choice for carbon mitigation policy in China．