The highly ordered TiO2 nanotubes (NTs) were fabricated by the anodic oxidation method.Their morphology,structure and crystalline phase were characterized by scanning electron microscopy (SEM) and X-ray diffractometer (XRD).The effects of morphology,specific surface area,pore structures and photocatalytic activity of the TiO2 NTs were investigated.UV-vis spectra analysis showed that its light absorption had been extended to the visible light range.The photocatalytic activity of the as-prepared samples was evaluated by photocatalytic oxidation of gaseous HCHO and MB aqueous solution.The samples had better adhesion strength in the dark and showed a higher photocatalytic activity than nanoparticles.Especially,with ultraviolet light pretreatment,the nanotubes exhibited more stable active for photocatalytic decomposition and the photodecomposition rate remained at high level after 3 cycles of the photocatalysis experiment.Thus,how the number of surface active group ·OH increased and the mechanism for the great improvement for the photocatalytic activity are discussed.