To improve the corrosion resistance of the 42CrMo alloy, a Stellite-6 coating was prepared on the surface of the 42CrMo alloy by laser cladding. The average corrosion rate and electrochemical characteristics of the Stellite-6 coating in a 3.5% NaCl solution were studied through an immersion experiment and electrochemical workstation. After the immersion experiment, the samples were analyzed via scanning electron microscopy (SEM). The test results show that the average corrosion rate of the laser cladding Stellite-6 coating is considerably lower than that of the matrix. In addition, the corrosion behavior of the coating in a NaCl solution is mainly pitting corrosion. Laser power considerably affects the quality of the cladding layer. When the laser power is 2500 W, the open circuit potential is -0.15 V, self-corrosion current is 3.294×10 ^-3 A/cm ², and impedance is 6742.5 Ω·cm ². Furthermore, the nucleation and grain growth rates of the molten pool increase, the grain is refined, the microstructure of the molten pool primarily contains fine equiaxed crystals, and the structure is more dense and uniform. The Cr₃C₂ passivation film formed on the corrosion surface inhibits the anode activity. In addition, the passivation film is clearly protective, which improves the corrosion resistance of the coating.