Abstract The determination of race conformity of ball bearing is mainly based on the classical fatigue life theory; however, besides the fatigue life, skidding may also become the main concern due to high frictional heating in high-speed application; therefore the strategy of race conformity determination should be changed accordingly. This paper investigates the influences of race conformity on the contact characteristics and motion of ball based on the developed dynamic model for angular contact ball bearings. The results show that the race conformity has a significant influence not only on the contact pressure between ball and raceways, but also on skidding of ball on raceway, which implies that the race conformity should be optimally determined according to the different applications.