To improve surface hardness of dental implant made of pure titanium (Ti), titanium nitride (TiN) coating was introduced. However, studies revealed that TiN only showed osseointegration similar or inferior to that of Ti. Therefore it is necessary to improve the biocompatibility of TiN for dental implant coating. In the present study, TiN coating was prepared on pure Ti substrates and hydrothermal treatment was conducted to modify its surface properties. It was found that, TiN surface was partially oxidized after treatment and calcium (Ca) was successfully combined onto its surface. Surface morphology, roughness and hardness were not affected after treatments below 140°C and wettability was obviously improved.