Cobalt modified TiO2 nanotube was prepared by wet impregnation method from anodized nanotube. The microstructure and phase characteristic were studied by SEM, EDX and XRD analysis. The photocatalytic degradation of methylene blue under UV illumination was studied. Enhanced degradation efficiency could be obtained after sodium borohydride reducing. For the samples using low concentration of CoCl2 in wet impregnation process, the degradation efficiency increased with the increase of CoCl2 concentration and for high concentration, the degradation efficiency decreased. With increasing the post-treatment temperature, the degradation efficiency decreased.