Abstract: In view of the explosion response test in the cabin of warship structure, the marine special steel is expensive, which greatly increases the test cost, so the study on the equivalence of ordinary steel instead of special steel in the cabin explosion response test is carried out. In order to determine the equivalent relationship between targets with different materials, based on the principle of similarity of deformation at the central point of target structure, and considering that the target is not broken, the method of equivalent replacement of target materials is proposed by using the method of dimensional analysis. The finite element analysis software ATUODYN is used to simulate the process of explosion load acting on four different types of steel target plates of 921A steel, 907A steel, Q235 steel and Q355 steel in the closed space. the maximum error between the calculated results and the test results is 5.6%. The correctness of the numerical simulation method is verified. Through the fitting of the equivalent plate thickness obtained by numerical simulation, combined with the empirical formula between the equivalent plate thickness and dynamic yield strength of target plates of different materials, it is verified that the equivalent method of different types of steel target plates under the explosion load in the cabin has rationality and good applicability. It provides a theoretical basis and data reference for the cabin explosion test with ordinary marine steel instead of marine special steel.