Abstract: Since the full-scale ship collision experiments are hard to perform, reduced scale model tests are conducted to investigate the resistance characteristic. The impact response of the prototype can be transformed from the experimental results of the reduced scale model tests through the similarity law. However, the similarity law is influenced by many factors. Two reduced scale and a prototype stiffened plates are designed to perform the low-velocity impact tests, and the impact resistance responses are obtained. Thereafter, similarity of the impact resistance is analyzed considering the influences of plate parameters (plate thickness, strength and strain rate) and impact parameters (the striking mass and the striking velocity). The results demonstrate that the strain rate and impact parameters influence the similarity law slightly. The plate thickness and strength can influence the similarity law. According to the proposed analytical equations of impact resistances in the large deformation and tearing processed, the reduced scale model test results can be transformed to that of the prototype by correcting the similarity law. The results can provide some guidance for the crashworthiness assessment of full-scale ship structures.