Surf-Riding/Broaching is one of the second generation intact stability failure modes of ships, but due to its strong nonlinearity and uncertainty, there are relatively few researchers. At present, the calculation method for the first and second layer vulnerability criteria of Surf-Riding/Broaching has reached international consensus, while the direct numerical evaluation of Surf-Riding/Broaching is still under research. Direct numerical evaluation is mainly based on the four degree of freedom MMG maneuverability equation to study the motion performance of ships under regular waves. However, in the actual navigation process of ships, the wave drift force will inevitably affect the ship’s motion state, especially the influence of the yaw moment on the ship. On the basis of summarizing previous research results, this article improves the MMG maneuverability equation by adding wave drift force to the wave force term, and studies the ship Surf-Riding/Broaching considering the influence of wave drift force. Taking the ITTC ship A2 fishing vessel as an example, numerical simulations were conducted on its motion state under different influence of initial yaw angle. The research results can provide technical support for the second generation complete stability.