Clearance is an important technical parameter for the cooperation of rolling bearings, which directly affects the bearing performance, vibration, noise, wear, temperature rise, service life and mechanical running accuracy. The basic dynamic load rating of the bearing varies with the size of the clearance. The basic dynamic load rating in the bearing sample is the recommended value for the bearing working clearance to zero. If the clearance is too large, the number of bearing rolling elements is reduced, the bearing capacity is reduced, the rolling contact surface stress is increased, the running precision of the bearing is decreased, the vibration and noise are increased, and the service life is shortened; if the clearance is too small, the bearing heat is caused. The temperature rises and even causes the bearing to bite during operation. Therefore, it is necessary to choose the bearing clearance according to the bearing type and working conditions. The radial clearance of the bearing includes the original clearance, the assembly clearance and the working clearance. The working clearance directly affects the service life of the bearing and is affected by factors such as installation conditions and working conditions.