TiO2 nanotube arrays were prepared by anodic oxidation at a constant potential in organic electrolytes (NH4F/glycerol, NH4F/ethylene glycol). The effects of anodic potential, anodic time and electrolyte composition on the nanotube morphology were investigated. A growth mechanism of TiO2 nanotube arrays in organic electrolytes was proposed. The results indicated that a much wider range of anodic voltage and longer anodic time for the preparation of TiO2 nanotube arrays were required in organic electrolytes. Furthermore, TiO2 nanotube arrays with different morphologies could be fabricated in organic electrolytes with different water contents. The large coefficient of viscosity and the low oxygen content of the organic electrolytes improved the growth velocity of the nanotubes, at the same time controlled their corrosion velocity, resulting in forming longer nanotubes in the electrolytes. Since the growing velocity of nanotube arrays in NH4F/ethylene glycol was bigger than that in NH4F/glycerol, longer nanotubes (64 μm) could be obtained in NH4F/ethylene glycol.