Abstract: In order to improve the service life of the coal slurry feed combustion mixer after overlay welding repair,four kinds of overlay welding wires were designed as filler materials,compared with UMCo50 welding wire,and the TIG welding method was used to prepare overlay welding layer on UMCo50 plate. Through high-temperature oxidation test,high-temperature molten salt corrosion test and high-temperature wear test,the high-temperature corrosion resistance,high-temperature oxidation resistance,high-temperature wear resistance of the five kinds of welding wire overlay layer were compared and studied,and X-ray diffraction analysis test(XRD),scanning electron microscopy(SEM) and energy spectroscopy(EDS) were used to analyze the microstructure and phase composition of the overlay layer. The results show that the microstructure of UMCo50 overlay layer is a planar crystal with a cyto-like substructure,and the matrix is all cobalt-based solid solution. The microstructure of the surfacing layer of the four types of welding wires designed is mainly dendritic cobalt-based solid solution,and carbides and low melting eutectices are distributed between dendrites. The solution strengthening of W,Mn,Si and other elements added to the welding wire and the second phase strengthening formed by the precipitated WC can improve the hardness and wear resistance of the surfacing layer,increasing Cr content and reducing the Fe content can improve the high temperature oxidation resistance and corrosion resistance of the overlay layer.