Abstract: For the complex characteristics of the torsional vibration analysis of hybrid vehicle， a P2 hybrid SUV(sport utility vehicle) was taken as a research object， and the transmission system concentrated mass model was established to analyze the inherent characteristics and excitation response characteristics. Then， based on AMESim simulation software， the influence factors of torsional vibration of transmission system were analyzed， and the sensitivity of main parameters such as clutch stiffness and damping was studied. The influence characteristics of torsional vibration are discussed in detail. The simulation results indicated that changing the damping stiffness of the clutch will affect the inherent characteristics of the transmission system and change the resonance peak value and frequency; increasing the damping of the clutch will reduce the peak value of the attenuation resonance of the transmission system， but was not good for vibration elimination at high speed.

Key words: hybrid power, drive train torsional vibration, concentrated mass, inherent characteristic analysis, sensitivity analysis