The highly ordered and vertically oriented pure TiO₂nanotube arrays (TONTAs) are synthesized by anodic oxidation of titanium foils in fluoride-based electrolytes under different temperatures and voltages. Then TONTAs are treated at different temperatures. X-ray diffraction (XRD) patterns show that its structure is anatase at 500 ℃ with the temperature increasing to 700 ℃, the most of anatase will transform to rutile, the nanotube arrays form granular titanium oxide, while at 900 ℃, anatase will transform to rutile completely. The experimental results of photocatalytic degradation of methylene blue solution show that the cobalt-manganese co-doped TONTAs have good photocatalytic degradation efficiency.