Ti-O film is a kind of potential biomaterial may be applied in medical devices. But the mechanism of its good biocompatility is not so clear. This study revealed that when Titanium oxide contact with macrophage and plasma, the activation, adhesion and secretion of inflammatory molecule MCP-1 of macrophage is lower than reference material. Ti-O film also show minor contact activation to plasma. So reducing the host reaction including contact activation and inflammation may be the important reason for the good biocompatibility of Ti-O film.