Abstract: According to the abnormal vibration problems of EMU train in the cross-line operation, by measuring the wheel tread, rail profile and through vehicle vibration test, the causes of abnormal vibration are analyzed from angles of rail/wheel contact relationship and vibration transmission characteristics. Due to different rail profiles, the maximum wear position change of wheel treads is a long-standing problem for EMU trains running on different lines, leading to vehicle adaptability decline in the later stage of wheel wear. The changes in rail profile cause bad wheel-rail matching when trains running across lines, therefore the energy of bogie hunting will increase and be transferred to the car body by the second suspension, leading to the abnormal car body vibration.