Possessing excellent bio-compatibility and mechanical performance, Ti-6Al- 4V (TC4) alloy is widely used as implant. Aiming at solving the problem of poor surface wear properties and improving bio-compatibility of TC4 alloy, friction stir processing(FSP) is applied to it filled with TiO2 powder in the groove to realize surface modification and build nano-sized composite biomedical material. Change in microstructure and its relationship with mechanical performance such as hardness will be discussed. A series of experiments in biology, including cytotoxicity test, cell culture, adhesion, proliferation and alkaline phosphatase activity is carried out to verify bio-compatibility of the material, compared with original TC4. The improved material is expected to provide a better environment for cells to grow.