Titanium oxide nanotube arrays were fabricated from a pure titanium foil with invariable anodizing voltage. CdS nanoparticles were then deposited upon the TiO2 nanotube arrays by electrochemical deposition method. And it was used to degrade the methyl orange. Results showed that CdS nanoparticals were evenly distributed upon the surface of the nanotube arrays and the doped nanotube arrays has better photocatalytic properties. The degradation of the methyl orange increases from 57.1% to 76.4% and the removal of the COD increases from 49% to 70.6% after 2 hours of irradiation