Highly ordered Mg(OH)₂ nanotube arrays were prepared inside the pores of porous anodic alumina membranes (AAM) by a simple chemical deposition method. The obtained Mg(OH)₂/Al₂O₃ composite membranes were used to remove nickel ions from wastewater with high removal efficiency. Furthermore, after heating the membranes that contained initial absorbed matter, the resulted MgO/NiO/Al₂O₃ metal-oxides nanostructures still showed nice performance of removing Ni²⁺. This composite AAM system and its preparation on a large scale have been discussed, showing potential application in treatment of wastewaters containing heavy-metal ions.