Because rails wear down after long-term use, laser cladding technology is used to repair damaged surfaces. Using U75V rail as base material, we optimize the process parameters of multilayer and multipass laser cladding. The results show that optimal process parameters is laser power of 900 W, cladding speed of 600 mm/min, feeding speed of 7.58 g/min, overlapping ratio of 58.8%, Z-axis lifting amount of 0.6 mm and preheating temperature of 200 ℃. There are many equiaxed grains in multilayer and multipass cladding areas, but acicular martensite is present in heat-affected areas. Hardness of the cladding zone is not much different from that of a base material: 480 HV in the cladding zone and a maximum of 430 HV for the base material. Under the effects of martensite, the hardness of the heat-affected zone is about twice that of the base material. Wear resistance of the cladding layer is slightly lower than that of a base metal.