Abstract:This paper introduces the national and local policy requirements for ultra low emission technical transformation of coal-fired power plants, one 660MW units of a certain power plant as the reformed object, on the basis of research on the ultra low emission technology of other power plants and environmental protection companies, and combined with the original environmental protection facilities and pollutant emission situation in a power plant , the technical route of ultra-low emission transformation is selected for less investment and short period of work, the scope of ultra low emission equipment modification is determined,the technical transformation of ultra-low emission of flue gas for NO.2 unit is successful,The average emissions of sulfur dioxide, nitrogen oxides and soot were 22 mg/Nm3, 34 mg/Nm3 and 2 mg/Nm3 after transformation, which were all in line with the 35, 50 and 10 mg/Nm3 standard requirements of national coal fired power plants, It is possible to reduce sulfur dioxide 750t/ years, 500t/ years of nitrogen oxides and 80t/ years on the original basis,which has good environmental and social benefits.Some problems in the transformation of ultra low emission technology are analyzed, and the proposed solution is to provide reference for the power plant which has not been reformed or is being reformed.