[Objectives]The port guard structure is the key part to protect the safety of the ship when berthing, for studying the dynamic coupling effect of "hull-guard-dock" during the ship berthing.[Methods]Using the nonlinear finite element method, the port side and port guard structure finite element model was established to simulate the dynamic evolution of speed, stress and energy during ship berthing.[Results]The results showed that when the port contacted the dock, the ship speed decreased to zero and the dynamic deformation and interaction force of the guard structure were the maximum.When the ship is berthing, the guard board shows a strong energy absorption capacity, accounting for about 70% of the initial total kinetic energy of the ship, and the hull structure is well protected. [Conclusions]With the improvement of the initial berthing speed, the port protection efficiency has a decreasing trend. After comparative analysis, the ultimate berthing speed of the target ship is 2.5 sections, and the recommended safe berthing speed is 2 sections, which can be used as a reference for the ship berthing speed limit and the hull structure energy absorption design.