The torsional vibration is a kind of particular vibration form which exists in the work process of the vehicle’s transmission. It is easy to cause the noise and vibration of the vehicles, which will affect the riding comfort and even lead to serious safety problem. On the basis of mechanism analyzing of the torsional vibration, this paper studies on the torsional vibration of the vehicle’s transmission by order analysis method. Through the torsional vibration test under a certain working condition on test bed, the order analysis method is proved to be valid and accurate. So it can provide reference for the design of the transmission and its improvement.