Abstract: Inconel 625 nickel-based alloy was cladded on the surface of 316L stainless steel substrate using TIP-TIG (hereinafter referred to as TT) welding technology. Three key welding process parameters, namely welding current, welding speed, and wire feed speed, were selected. Overlay welding experiments were carried out via orthogonal experimental design, and the optimal welding process parameters were determined and optimized using weld dilution rate as the core evaluation criterion. The microstructure characteristics of the welded joint under the optimal process were observed and analyzed by optical metallographic microscope. Mechanical properties were tested through tensile tests and Vickers hardness tests. Furthermore, the corrosion resistance of the overlay coating and the base material was systematically evaluated by ternary chloride molten salt corrosion tests at 600 ℃, combined with characterization methods such as scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The results show that the overlay coating exhibited the best comprehensive performance when the welding current was 150 A, welding speed was 2 mm/s, and wire feed speed was 3.13 m/min. The tensile strength and elongation after fracture of the 316L base material were 633.50 MPa and 55.90%, respectively, while those of the overlay coating were 751.90 MPa and 50.20%, respectively. The overlay coating of the welded joint exhibited the maximum harolness of 219.60 HV, the substrate ranked second with 174.30 HV, and the heat-affected aone had the minimum hardness of 155.10 HV. After corrosion in ternary chloride molten salt at 600 ℃, the average corrosion rate of the substrate was 17.75 mm/a, whereas that of the overlay coating was only 3.35 mm/a, which was about one-fifth of that of the base material.