Anatase-dominated anatase/rutile mixed-phase TiO2 nanotubes were prepared by decorating TiO2 on the hydrothermally synthesized TiO2-derived nanotubes via liquid phase deposition and subsequent annealing. The morphology and structure of as-prepared TiO2 nanotubes were characterized by transmission electron microscopy, X-ray diffraction, Raman spectra, and UV-Vis diffuse reflectance spectra. The separation efficiency of photogenerated carriers was investigated by photoluminescence spectra. The photocatalytic activity was evaluated by methyl orange decomposition under UV illumination. The results indicated that the mixed-phase TiO2 nanotubes consisting of anatase and rutile (82/18 w/w) were successfully fabricated. Due to the synergistic effect of mixed anatase and rutile phases, the anatase-dominated anatase/rutile mixed-phase TiO2 nanotubes exhibited superior photocatalytic activity. The apparent rate constant k of the photocatalytic reaction for the TiO2 nanotubes with and without decoration was 0.0528 and 0.0126, respectively.