The stability of porous alumina template has been investigated when the template acts as cathode and reacts in different pH electrolytes. The cathodic reaction can be separated into four stages. In particular, there exists an autocatalyse reaction, which causes the erosion of the porous template for the local high pH solution. Hence, the template is relatively stable in lower pH electrolyte. After electrochemical reaction, long and radial distributed nanowires are got at the surface of cathode for the etching of the fluid high pH solution.