Abstract: Aiming at the abnormal vibration phenomenon of the carbody in the operation of an electric multiple unit，which is the carbody chattering accompanied by the bogie hunting movement. An online test on the vehicle is conducted，and it is found that the vehicle with a large tread conicity state exhibits insufficient stability when running at a higher speed，causing the hunting frequency of the bogie to continuously increase and approach the diamond-shaped deformation modal frequency of the carbody，consequently leading to the carbody to chatter. To improve the running stability of the vehicle，a two-step progressive optimization method that combines analytical optimization and simulation optimization is proposed to optimize the parameters of the anti-yaw damper，the method is abbreviated as AOSO. Furthermore，the optimization performance is experimentally verified. The results indicate that after optimization，the critical speed of the vehicle under the condition of worn wheel is significantly improved，there is no obvious hunting motion of the bogie，and carbody chatter is significantly decreased.