Abstract: Without any thickening agent addition, Al foams with porosity ranging from 62.4% to 83.3% and fine cell size were fabricated successfully via melt-foaming method by using CaCO3 as foaming agent and the addition of 1.0wt%-3.0wt% Mg in Al matrix. The effect of addition of Mg on the foaming ability of Al melt and the compressive property of Al foams were studied. The results indicate that the moderate addition of Mg in the Al melt was beneficial to form Al foam with fine cell size. Gas release reaction of CaCO3 in the Al melt produces solid oxide particles, which can thicken the melt effectively and lead to formation of small size pores. The pores with micrometer level size in the cell walls lead to a decrease of compressive strength of Al foam.