Abstract: The run-out of the outer diameter of the hub bearing usually refers to the run-out of the outer diameter of the bearing during operation, which will cause bearing wear, reduced working accuracy and vibration. Taking the reduction of the outer diameter run-out level of the third generation hub bearing as the research objective, the main factors affecting the accuracy are analyzed in detail. It is concluded that the coaxiality of the outer diameter of the inner flange is a significant factor affecting the run-out level of the hub bearing. Aiming at this factor, the existing process system is comprehensively analyzed and improved, and two technical schemes are put forward, so that the qualified rate of the finished hub bearing can be increased to above 96% under the technical index of the loading outer diameter run-out ≤ 0.03 mm.