Abstract: In recent years, there have been multiple ship collisions and collapse accidents on piers of non-navigable and low-navigable channels in our country. To better cope with the anti-ship-collision design for small-sized bridge piers and further expand the applicability of the bow equivalent dynamic stiffness model, the original stiffness model is modified in this paper based on ship collision with a rigid wall. Firstly, the results of small-sized piers under the original stiffness model are analyzed. The deformation characteristics of the bow during the collision process are studied. Then, the bow stiffness of 500 DWT~5000 DWT ships in inland river is corrected according to the size range of 1.5 m~7 m between the height of the cap and the width of the pier. Otherwise, the situation of the non-navigable circular pier is considered. Finally, the accuracy of the revised model is analyzed for common pile-column piers and double limb thin-walled piers. The results indicate that as the contact area decreases, the use of a simplified dynamic stiffness model of a rigid wall for calculation will gradually lead to errors, which will cause a sharp increase in the cost of subsequent protective engineering. The modified equivalent dynamic stiffness model can more accurately describe the dynamic response and damage state of bridges. Compared with the original stiffness, the applicability of the revised stiffness model has been further expanded, which can provide a useful reference for bridge anti-collision design.