Abstract: Objectives To improve the efficiency of ship motion prediction and address the issues of high computational resource consumption and long time-consuming in ship design using viscous flow simulation, a viscous-potential flow coupling method was established to predict ship motion by combining potential flow and viscous flow theories. Moreover, a systematic analysis of the computational efficiency advantages of this method in different wave environments was conducted. Methods Taking the Wigley ship as an example, the flow field around the hull was divided into inner and outer domains. The efficient transmission of waves and the solution of ship motion were achieved by setting up the coupling region of viscous-potential flow. Results By analyzing the waves, heave and pitch under different wave heights and wavelengths, and comparing them with the results of model tests and viscous flow simulations, the reliability of the viscous-potential flow coupling method to predict ship motion was verified. Meanwhile, by statistically calculating efficiency indicators such as computation time, grid requirements, computational efficiency, and speed-up ratio, the computational efficiency advantages of this viscous-potential flow coupling method in ship motion simulation were demonstrated. In addition, by analyzing the distribution characteristics of efficiency indicators under different wave slopes, the environmental sensitivity of the computational efficiency advantages on this method was further illustrated. Conclusions The energy-efficiency analysis of the viscous-potential flow coupling method will contribute to the establishment of an autonomous trade-off mechanism between accuracy and computational resources in future ship optimization, providing technical support for the widespread application of the viscous-potential flow coupling method.