TiO2 nanotubes were deposited on FTO substrates by one-step electrochemical deposition. TiO2 nanotube arrays exhibit high orientation perpendicular to the substrates, with average external diameter of 150 nm and wall thickness of 30 nm. Besides, a dense layer with small nanoparticles on the surface of the substrate can be found, which indicates that the TiO2 nanotubes were grown from this dense layer. The microstructure of TiO2 nanotubes can be tuned by adjusting reaction temperature and aging times of precursor solution. If decreasing reaction temperature, nanotubes with smaller diameter and low density can be obtained. More importantly, the aging time of precursor plays a key role on the formation of hollow structure. The bio-sensor properties were characterized by detecting photoluminescence from TiO2 nanotube films covered with dye labeled DNA under irradiation by red lasers. The nanotubes showed higher photoluminescence, which might be caused by higher density and high crystallinity of nanotubes.