Abstract: The thermal decomposition characteristics of CaCO3 powders in aluminum melt and N2 were analyzed by the thermal analysis method. On the basis, foamed aluminum was prepared with CaCO3 as thickening and blowing agent. The results show that the decomposition temperature of CaCO3 in the aluminum melt was lower by 20-30 ℃ than that in N2, the decomposition was uniform and stable at the constant temperature of 700 ℃, which matched with the foaming temperature. During the foaming process of aluminum melt, CaCO3 decomposed to CO2 only, no CO. The foamed aluminum prepared by using CaCO3 as thickening and blowing agent had uniform porosity and spherical or near spherical pore structure.