The effect of Ba addition on the thermal stabilization of $gamma$-$Al_2O_3$ powders were studied. Ba additive was introduced into $gamma$-$Al_2O_3$ powders by wet impregnation of $Ba(No_3)_3$.$6H_2O$. Ba additive was proved to be effective on the thermal stabilization of $gamma$-$Al_2O_3$ powders by suppression of sintering. The optimum content of Ba was determined by 5 mol%, through the calcinations temperature range. It is suggested that the main reason of thermal stabilizaton is the substitution effect of large $Ba^{2+}$ ions into the $Al^{3+}$ sites, which suppressed the surface diffusion of $Al^{3+}$ ions.