A wheelset bearing is a critical part of high-speed train bogies; its running status directly affects the safety and stability of the trains. A wheelset bearing vehicle track dynamic analysis model with a flaw in the wheelset bearing outer raceway is established, and the dynamic response of the wheelset bearing cage is calculated through simulation analysis software. The calculation results indicate that when the wheelset bearing outer raceway is defective, the change amplitude of wheelset bearing roller angular velocity increases, and the wheelset bearing roller angular velocity also has periodic mutation. As the flaw width of wheelset bearing outer raceway expands, the contact behavior between the wheelset bearing roller and the wheelset bearing outer raceway intensifies, and the impact of the wheelset bearing roller on the cage increases, and the relative deviation of the position of the center of mass gradually increases, causing the decrease of the stability of the wheelset bearing cage.