The identification and sensitivity analysis of compound vibration is the basis of vibration control of vehicle body. In the paper, the mechanism and key influencing factors of compound vibration are analyzed by establishing the dynamic mathematical model with 11 degrees of freedom, and the experiment method for identifying compound vibration is put forward. The sensitivity of influencing factors of compound vibration of the body is analyzed by establishing a rigid-flexible coupling dynamic simulation model. The results show that vertical vibration, roll vibration and pitch vibration are the main forms of the vehicle body vibration, the key influencing factor of vertical vibration is rear suspension stiffness, the key influencing factors of roll vibration are lower control arm length and rear suspension damping, front suspension stiffness and rear suspension stiffness are the key influencing factors of pitch vibration. The research results provide a theoretical basis and reference for mastering the composition and formation mechanism of compound vibration of vehicle body.