Abstract: A dynamic modeling for angular contact ball bearings under constant preload was established.According to the constant preloaded mechanism,considering the gyro force and centrifugal force,based on Hertz contact theory,this paper proposed a dynamic nonlinear model for angular contact ball bearing.The model was solved by the numerical iteration to obtain the angular contact bearing dynamic parameters and dynamic contact parameters. The parameters include the dynamic normal contact force and contact angle,maximum compressive stress and axial displacement,contact pattern and stiffness value,etc of bearing inside and outside ring. In order to validate the correctness of the model,a test device equipped with a constant preloaded bearing group was designed. By measuring the relative displacement of the bearing inside and outside ring in different conditions,the accuracy of the model was proved. This modeling method provided a theoretical basis to calculation bearing calorific value,fatigue life and optimizing bearing ring channel curvature radius further.