The infiltration casting fabrication process based on spherical CaCl2 space-holders and the compressive behavior including the mechanical performance and energy absorption capacity of open-cell aluminum foams were investigated. Open-cell aluminum foams with different porosities in the range of 63.1％ to 87.3％ can be fabricated by adjusting compression ratios of CaCl2 preforms prepared by precision hot-pressing. The compression tests show that a strain-hardening phenomenon always occurs especially for open-cell aluminum foam with low porosity, resulting in the inclining stress-strain curve in the plateau region. The energy absorption capacity of open-cell aluminum foam decreases with increasing porosity when compared at the same strain. However, when compared at a given stress, each foam can absorb the maximal energy among the five foams in a special stress range. Additionally, open-cell aluminum foam possesses the maximum energy absorption efficiency at its optimum operating stress. At this stress condition, the foam can absorb the highest energy compared with other foams at the same stress point. The optimum operating stress and the corresponding maximal energy absorption decrease with increasing the porosity. The optimum operating stress for energy absorption can also be determined similarly when taking into consideration of the lightweight extent of foams.