The geometric structures, energetic and electronic properties of global minima of the AlBe_n (n = 1–12) clusters have been systemically studied by using the hybrid density functional theory [B3LYP] and coupled cluster [CCSD(T)] methods. It is found that the impurity Al atom is externally bound to the host Ben framework and its maximum coordination number is six. Besides, the geometries of AlBe_n bear close resemblance to either local or global minimum structures of Be_n+1. The AlBe₃ and AlBe₈ clusters exhibit high relative stability among the AlBe_n clusters, which is reflected by the evolutions of average atomic binding energy, dissociation energy, second difference in energy, adsorption energy of Al, and HOMO-LUMO gap with cluster size. In comparison to the pure Be_n+1 clusters, AlBe_n exhibit larger binding energy values, whereas they are more polarizable.