Abstract: Aiming at the side guide plate of 718 material with wear failure,the gas shielded welding technology was used to repair the damaged working face,and influence of process parameters on microstructure and properties of the surfacing layer was studied to optimize the process scheme. The results showed that,under different welding shielding gas and welding heat input,the surfacing layer metal was well fused with the base metal and there was no welding defect. Microstructure of the surfacing layer was mainly composed of martensite,a small amount of ferrite and retained austenite,and its microhardness and wear resistance were higher than those of base metal. Wear resistance of the surfacing layer with welding protection gas 20% CO₂+ 80% Ar was higher than that of the surfacing layer with welding shielding gas 100% CO₂,and wear resistance of the surfacing layer with large welding heat input was higher than that of the surfacing layer with small welding heat input.