Objective To improve the photocatalytic and hydrophilic properties of 316L stainless steel surface. Methods N doped TiO2 thin films were obtained by thermal oxidation of titanium nitride films, which were prepared by plasma surface alloying on stainless steel substrate. The resultant thin films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and ultra violet-visible absorption spectroscopy (UV-Vis) methods. The pho- tocatalytic properties and hydrophilicity of N doped TiO2 thin films were studied through photocatalysis and hydrophilicity tests. Results XRD patterns showed that anatase type TiO2 existed in the thin films after thermal oxidation at 450 ℃ in air for 2 h. According to XPS, residual N atoms partially occupied O atom sites in the TiO2 lattice. The band-gaps of TiO2 and N-doped TiO2 were 3. 25 eV and 3. 08 eV, respectively. A uniform and dense surface containing three-dimensional homogenous protuberances growth of grains was observed in SEM images of thin films after thermal oxidation. The experimental results of degradation of Methylene blue solution under visible light indicated that photocatalysis efficiency of N doped TiO2 film was better than that of the undoped film. The ultimate degradation rate of N doped TiO2 was 20% in visible irradiation for 150 min. The N doped TiO2 films showed a higher hydrophilicity and the contact angle was lowered to 8. 5° by Vis-irradiation within 30 min. Conclusion The N doped TiO2 film could effectively improve the photocatalytic and hydrophilic properties of stainless steel surface.