The Bi2Te3/Te multiple heterostructure nanowire arrays were successfully synthesized through a simple thermal annealing process of the supersaturated Bi-Te alloy nanowire arrays. On the basis of the systematic investigations of the thermal treatment processes, it is considered that the precipitation confined by porous anodic alumina (PAA) membranes leads to the spontaneous formation of the block-by-block structure. The self-assembled blocks in the heterostructure nanowires are single-crystalline, and the clear interface between neighboring blocks is flat and perpendicular to the wire axis.