Under the background of wide application of low nitrogen and oxygen combustion technology and deep peaking technology, the high temperature corrosion failure of water wall tubes is more serious in service process. The high-temperature corrosion behavior characteristics of the boiler water wall tube and high-speed arc spraying PS45 coated tube from a power plant were comparatively investigated. Moreover, the corrosion surface morphology, corrosion products compositions and corrosion cross section characteristics were systematically analyzed by means of SEM, EDS and XRD. The results show that, the high-speed arc spraying PS45 coating can effectively improve the high temperature corrosion resistance of water wall tubes, and the thickness of the surface corrosion layer is small. In the process of high temperature service, the PS45 coating shows better corrosion resistance due to its high content of Cr and Ni, and the thickness of the surface corrosion products layer is thin. However, the microscopic pores between the coating particles will lead to intrusion of high-temperature corrosion reactions, and even cause direct corrosion of the water wall tubes at the coating/substrate interface.