Dual mass flywheel (DMF) is an important vibration isolation component in the transmission system of the whole vehicle, which has an important impact on the torsional vibration of the transmission system. In this paper, the DMF CAE model is built by the theoretical analysis. The torsional stiffness characteristics of DMF under different working conditions are studied by the combination of test and simulation. Then, the torsional vibration analysis model of the transmission system is built, and the influence of different param-eters of DMF on the torsional vibration of the transmission system is studied by taking the speed fluctua-tion of the main and secondary flywheel in frequency domain as the evaluation index. The above work would guide the optimization of vibration, roar, gear knocking and other problems caused by the torsional vibration, and provide simulation analysis methods for the transmission system matching in the early stage of a vehicle project, which will effectively reduce the risk of torsional vibration problems.