According to theory of thermoelasticity, the paper deduces the formulas of the rolling bearing steel ball transient temperature, radial stress, tangential stress, radial displacement, and radial clearance, analyzes the influence of the temperature deformation on the radial clearance. The result shows that the radial displacement changes slowly on the surface, reaches the maximum when temperature becomes stable. The reduction value of the radial clearance is the linear function of the temperature and position. Fitness formula is adopted to calculate the radial clearance in the different temperature and radius. The error is less than 0.2% and 0.18%. The radial clearance formula is used to calculate the bearing’s maximum working temperature when the radial clearance reaches the standard radial clearance to ensure the reliable work of the bearing.