With the rapid development of high-speed craft, the novel aluminum alloy stiffened panel with floating girder is widely used to achieve light weight ship hull for economic and high performance. While the mechanical properties of this novel structure are rarely studied. In order to investigate the differences of ultimate strength and collapse behavior between the novel aluminum stiffened panel with floating girder and fixed girder, the uniaxial compression experiments of novel aluminum stiffened panel with floating girder and fixed girder were conducted. Test apparatus were designed to accomplish simply supported boundary condition, then the uniaxial compression experiments were performed, eventually the ultimate strength and collapse behavior of different panels were analyzed. The results of the experiments show that the ultimate strength of novel aluminum stiffened panel with floating girder is higher than the panel with fixed girder under uniaxial compression, which means this type of novel aluminum alloy stiffened panel with floating girder applied on the high-speed craft can improve the ultimate strength of the vessel. Furthermore, it was witnessed that the collapse mode of stiffened panel with fixed girder is tripping of web while that of floating panel is bucking of girder.