Samples of closed-cell aluminum foams are prepared by air-foaming aluminum melt, and two techniques are employed to obtain uniform and non-uniform aluminum foams under identical processing conditions. Experiment results show that the uniform-celled aluminum foam presents an overall 25% improvement of the yield strength over the one for the non-uniform cells with the same density, and a very precise relation between yield strength and density is obtained for the uniform-celled aluminum foam. The cell size uniformization does not affect elastic modulus significantly, and the uniformity of the aluminum foam cells decreases the energy absorption ability.