Based on finite element method, combined with numerical simulation, the calculation algorithm of ship-bridge collision effect is given. The general formula of impact force is derived at first. Then, in order to obtain the functional relationships between ship speed, ship weight and collision force, a four continuous rigid frame highway channel bridge is taken as an instance of real bridge, the influence of ship weight and ship speed on the impact force during the ship bridge collision was analyzed. By using ANSYS / LS-DYNA software, the three-dimensional simulation dynamic finite element model of ship bridge collision was established. Numerical simulation calculations were carried out for the crest value of impact force of the ship bridge under the above two factors. Subsequently, statistical fitting analysis was carried out on calculation results. Based on numerical simulation results, the linear function relationships between the crest value of impact force and the secondary root of the ship weight and the ship speed are obtained, which provides a basis for the crest value of impact force in bridge anti-collision design.