A process for preparing aluminum-steel-high pressure gas phase composite foam belongs to the porous foam metal field, which comprises permeating hollow steel balls in a pressure chamber with high pressure gas in pressure cavity, filling gaps between steel balls with aluminum with low fusing point or aluminum alloy flux, and then sintering to seal high pressure gas so as to seal high pressure gas phase into obturator foramens of aluminum-steel composite foam, thereby obtaining aluminum-steel-high pressure gas phase composite foam. The process seals high pressure gas phase into obturator foramens of foam metal, and increases the intensity of foam metal by utilizing gas phase and pressure, which is a novel effective method to increases the intensity of foam metal material.