Based on the system analysis of dynamic equations group of high-speed angular-contact ball bearing, an analysis to find the ultimate variables of the adjunct equations was given, and a chart about coupled variables was obtained which showed that the contact angle are the ultimate variables. Based on above-mentioned analysis, according to the feature of the bearing under axial load, an algorithm has been put forward, which took the contact angle as the iterate variables. Based on the present calculation results, an analysis was given, which showed that the increment of internal contact angle is larger than that of external contact angle, the analysis would be helpful to define the contact angle field. By using the method of contact angle iterate, an example was given, which verified the analysis of increment of contact angle is correct. So the search field of contact angle has been reduced half, and the calculation is simplified obviously.