Abstract: Objectives In order to explore the ultimate bearing capacity and collapse buckling characteristics of long-span double-layer plate frame structures under axial compression, Methods In this study, a typical ship long-span double-layer plate frame structure was selected as the research object, and the axial compressive ultimate strength test of the long-span double-layer plate frame structure was designed and carried out, and the test results were compared with the simulation. Results The test results show that the overall buckling instability of the upper and lower decks is the main reason for the collapse of the long-span double-deck structure, and the comparison with the simulation results verifies that the subload effect of the axial compressive load has a significant impact on the ultimate bearing capacity of the structure. Conclusions In the actual simulation evaluation, the load sharing effect should be included in the analysis to obtain the safety and conservative evaluation results.