A double mass flywheel is an advanced technology of automobile power transmission. Through reasonable design of mass block and elastic element, efficient torque transmission and vibration isolation can be realized. This design makes the double mass flywheel play an important role in the automobile power transmission system. In this chapter, the mechanism of torsional vibration and its influence on vehicle performance are analyzed, and the torsional vibration characteristics under different working conditions are simulated. The factors affecting the torsional vibration characteristics of the two-mass flywheel are discussed. The results show that the optimized two-mass flywheel has achieved remarkable results in reducing torsional vibration amplitude and improving power transmission efficiency.