The ship propulsion shafting with paralleling engine withstands various kinds of torque im-pact during different operation conditions. The traditional frequency domain calculation method cannot calculate the shafting response under the torque impact load. In order to obtain the dynamic response of the propulsion shafting, a multi-mass point model for the calculation of transient torsional vibration of the propulsion shafting is established by the classical lumped parameter method. In order to obtain an accurate calculation model, damping and ex-citation are specifically studied in the paper. Based on the Newmark-β method, the time-domain torsional vibration calculation process of the propulsion shafting is proposed, and the dynamic response of the shafting during the impact is obtained. Taking the electric propulsion system with two paralleling motors as an example, the transient torsional vibration simulation is carried out. The influence of phase angle between different loads on the dynamic response is discussed, which provides a reference for calculating the transient torsional vibration of the propulsion shafting of the combined power plant.
