Abstract: Taking the high speed spindle as the research subject, the mechanical model of angular contact ball bearings was established to calculate the contact load of every ball with consideration of dimension errors through the mechanical analysis on the angular contact ball bearing support of the high speed motorized spindle. For a specific example, the influences of the axial load and radial load on the contact load of every ball were studied without considering the rolling element size error. The results show that if the axial load is a constant, the variation of the radial load will change the contact load distribution of the ball. The greater the radial load, the greater the difference between the maximum contact load of the ball and the minimum contact load of the ball. The influences of the dimension error on the contact stress and fatigue life of every ball of two situations were also studied. The first one is that every ball has no dimension error, and the second one is that every ball has a random dimension error. The results show that both positive and negative errors of the rolling element will change the force of each rolling element, and will reduce the life of the rolling bearing. The influences of the rolling machining accuracy on fatigue life of angular contact ball bearing were investigated, and then the concrete curves were obtained. The results show that the fatigue life of angular contact ball bearing will decrease rapidly as the machining precision decreases. The rate of decline rapidly increase when the accuracy is lower than the G40.