In order to understand the deformation mechanism and energy dissipation of solid buoyant material with different ratio of height to diameter under uniaxial compression loading, the desired experimental tests and numerical simulation were conducted. Firstly, the uniaxial compression test of solid buoyant material specimens with five different ratios of H to D is conducted by means of MTS-45 universal testing machine, while the mechanical response characteristics and failure modes are analyzed. Secondly,the simulation model of the solid buoyant material is proposed based on the results of uniaxial compression test and the macroscopic mechanical property of the solid buoyant material is described with ABAQUS finite element software. Results show that the bearing load stress circles of the solid buoyant material expand at the beginning of plateau stage and the dominant deformation mode is plastic compression during the plateau stage. As densification stage starts, the deformation mode transfers from symmetric biconcave disks to asymmetric slip deformation with the increasing ratio of H to D. The solid buoyant material is apt to shear failure, while the amount of absorbed energy of the failure process increases with the decreasing ratio of H to D, which presents plastic shear failure characteristics. On the contrary, with the increasing ratio of H to D, the material is apt to compression fracture failure．