Axle surface roughness has a great influence on its performance in application. In order to optimize the axle surface roughness, and to ensure the surface integrity of axle to meet the requirements, the testing analysis was carried out on the material of 20CrMnTi axle through experimental method. Under different grinding process parameters, the grinding surface roughness of the sample parts was studied, and the law of changing of surface roughness degree along with process parameters in the grinding was obtained. The optimal process parameters in match are given by combined with the actual conditions of process.