A preparation method of TiO2 nanotubes grown on the pore surface of foamed titanium and the growth mechanism of the TiO2 nanotubes were studied in this paper. A kind of porous foamed Ti-Ni alloy was prepared by vacuum sintering method that is similar to the preparation method of porous ceramics. The porous foamed alloy was modified: an anodic oxidation method was used to generate a layer of TiO2 nanotubes on the surface of the porous foamed Ti-Ni alloy. Besides, the growth mechanism of TiO2 nanotubes was researched through scanning electronic microscopy (SEM) method, and the influences both of the anode oxidation voltage and the time on the TiO2 nanotube structure were also investigated.