The mechanical behaviors of Al-3Si-2Mg-2Cu porous metal were studied by using compression test. The characteristic stress-strain curves showed three regions: a linear elastic region, a long plateau where stress maintains a certain level regardless of strain and final densification region. The compressive stress of plateau region was smooth and uniform after solution heat treatment, while that of the non-heat-treated showed peak value followed by a sudden drop. The difference between the two flow stress level explains that the deformation mechanism is changed from brittle to ductile fracture. The role of fine precipitate in the grains and grain boundaries was discussed with the help of microstructural observation during solution treatment.