The work aims to study the effect of relative density of spherical open cell aluminum foam in the quasi-static compression process on the compression properties and energy absorption of spherical open cell aluminum foam. Quasi-static compression experiments were carried out on three prepared aluminum foam samples with different relative densities. The experimental curves of spherical open cell aluminum foam samples with different relative densities were plotted with relevant software. From the analysis of experimental curves, when the relative density of aluminum foam increased from 0.35 to 0.392, the yield strength of spherical open cell aluminum foam increased by 3.2 MPa, but the maximum energy absorption efficiency decreased by nearly 2.4%. With the increase of relative density of aluminum foam, the higher the compression properties, the higher the compressive strength. Under the same strain, the aluminum foam with higher density has better energy absorption than that with lower density. The higher the relative density of aluminum foam, the lower the maximum energy absorption efficiency and the maximum ideal energy absorption efficiency.