The role of alloying elements in the dissolution of aluminium sacrificial anodes was investigated . The effect of indium on the electrochemical performance of anode and the relationship between indium and impurities , such as silicon and iron, were studied. The distribution of indium in aluminium alloy was detected . The electrochemical behaviour of In-implanted aluminium alloy was also studied . The experimental results indicate that indium activates the surface of aluminium alloy and improves the electrochemical performance of alloy containing more amounts of impurity . Indium combines with silicon and iron.More satisfactory properties were obtained when the alloy’s proportion of content of In to that of (Si+ Fe) is about 1 : (8 ~10). The electrochemical properties of Al alloy, especially the surface activity of the anode were improved by ion implantation . Indium segregates in the alloy . The amount of Si and Fe in the In-rich segregated phase is richer than that in the matrix. It is proposed that th The role of alloying elements in the dissolution of aluminum sacrificial anodes was investigated. The effect of indium on the electrochemical performance of anode and the relationship between indium and impurities, such as silicon and iron, were studied. The distribution of indium in aluminum alloy was detected. The electrochemical behavior of In-implanted aluminum alloy was also studied. The experimental results that that indium activates the surface of aluminum alloy and improves the electrochemical performance of alloy containing more amounts of impurity. Indium combines with silicon and iron. More perfect properties was obtained when the alloy’s proportion of content of In to that of (Si + Fe) is about 1: (8-10). The electrochemical properties of Al alloy, especially the surface activity of the anode were improved by ion implantation. Indium segregates in the alloy. The amount of Si and Fe in the In-rich segregated phase is richer than that in the matrix. It i s proposed that th