Some problems, such as distortion and cracking, can be observed in the laser cladding layers because of their non-equilibrium microstructure and residual stress. Herein, the tempering heat treatment is used to improve the comprehensive properties of a 420 martensitic stainless steel coating. Further, the effect of tempering temperature on the microstructure, mechanical properties, and corrosion resistance is investigated. The results denote that the as-cladded specimen mainly comprises martensite, austenite, and M₂₃C₆ carbide and that reversed austenite can be observed after the tempering treatment is conducted at 200 ℃ and 400 ℃. The tempering temperature affects the mechanical properties. The tensile strength (approximately 1800 MPa) and microhardness (approximately 530 HV) of the as-tempered specimens at low (100 ℃ and 200 ℃) and medium (400 ℃) temperatures are comparable with those of the as-cladded specimen. Furthermore, the elongation of the specimens increases with the increasing tempering temperature. However, the strength and microhardness considerably decrease and the elongation slightly decreases after high-temperature tempering treatment (600 ℃). Therefore, the as-tempered specimen at 400 ℃ exhibits optimum comprehensive mechanical properties but slightly lower corrosion resistance when compared with those of the as-cladded specimen and the commercial 420MSS martensitic stainless steel.