Thermosensitive polymer nanotubes can be fabricated within an aminopropylsilane-modified porous anodic aluminum oxide membrane by surface-initiated atom transfer radical polymerization (ATRP) followed by template removal. DSC experiments prove that the synthesized PNIPAM-co-MBAA copolymer nanotubes have a reversible thermosensitive behavior. The temperature-induced changes in dimension and shape of the nanotubes were studied by AFM in real time in an aqueous environment. It indicates that the nanotubes undergo a shape alteration from an "ellipse" to ''circular" shape in water upon heating to LCST or above.