Based on the vehicle dynamics theory, the torsional dynamic model of the elastic axle suspended direct drive system was established. By solving the system torsional vibration differential equation, the vibration reduction efficiency of the elastic coupling and its influencing factors were discussed. At the same time, a coupling structure suitable for the axle suspended direct drive system was proposed, and its key performance parameters were theoretically analyzed, designed and calculated. Finally, an example calculation and test verification were carried out by taking an axle suspended direct drive system of a certain urban rail vehicle as the design object. The results showed that the calculated value was consistent with the test value and met the design requirements.