Amorphous Ta-O films were synthesized by reactive pulse unbalanced magnetron sputtering system in this paper. Then the well-crystallized Ta-O films were obtained after they were annealed in vacuum at 800°C for 1h. Hydroxyl group on the surface of amorphous tantalum oxide films was prepared by plasma hydrogenation method. The phase structure was investigated by X-ray diffraction (XRD). The hydroxyl group was characterized using Fourier transform infrared spectroscopy (FTIR). The morphology and growth behavior of the vitro platelet adhesion on the as-deposited, annealed and plasma hydrogenated Ta-O films were analyzed through scanning electron microscope (SEM). The results showed that the quantity of platelet adhered onto the annealed surface were less than as-deposited and hydrogenised films. A new method of preparing hydroxyl group without coupling agents on the inorganic biomaterials has been studied by plasma hydrogenation.