Abstract: Based on implementation of the Air Pollutants Emission Standards for Thermal Power Plants of 2003 and 2011 versions, four scenarios were set up to simulate the PM_2.5 concentration in 2020 using WRF-CMAQ model system. The effect of implementation of the new standards was thus evaluated and the change of the PM_2.5 contribution by the thermal power plants(TPPs) investigated. The results showed that the implementation of the 2011-version emission standards could effectively reduce the PM_2.5 pollution, but the pollution was still serious in China. In 2020, implementation of the 2003-version emission standards, the contribution rate of the TPPs to PM_2.5 in 30 cities of China is 27.7%~34.8%, implementation of the 2011-version emission standards, the contribution rate of the TPPs to PM_2.5 in 30 cities of China is 12.2~19.6%, with the contribution rate of primary and secondary are 2.2%~4.4% and 10.1%~14.9% respectively.