Abstract: SO₃ in boiler flue gas not only pollutes the environment, but also causes damage to downstream equipment of boiler. Based on the investigation and comparison of the achievements and technical routes of SO₃ removal technology of power plant boilers at home and abroad, the engineering application of SO₃ removal technology in W-type flame boiler with alkaline dry powder adsorbent is realized. This paper analyzes the effect of the technology in controlling the differential pressure of the air preheater, the problems existing in the engineering application, and gives the countermeasures. At the same time, combined with the operation practice, it puts forward the methods and ideas to reduce the operation cost of the system.Thereby the SO₃ removal method,the problems and response which are need to pay attention to could be used as reference for peers.