For the development of Nickel Titanium NiTi)biomaterial devices,the study and improvement of cytocompatibility and biomechanical performances are of prime importance. Following the guidelines of the American Society for Testing Materials (ASTM), our study established that the cytotoxicity of NiTi was worse than that of pure Ti, Ti6A14V and 316L stainless steel. The deposition of plasma polymerized tetrafluoroethylene (PPTFE) thin film on NiTi surface improved cytotoxicity and corrosion resistance of NiTi alloys. The fatigue propertics were improved by various heat treatments and the degradation of the superelastic properties were tested by cyclic tension-tension tests.