Aluminum oxide film doped with cerium have been deposited by the MF reactive magnetron sputtering technique. With the deposition condition of constant power, 30min duration, Ar and O2 flow of 43 and 10ml/ min, the relationship of luminescent properties of Al2O3：Ce^3＋ films with the amount of Ce^3＋ incorporated in the films was studied. The presence of Ce^3＋ as well as the stoichiometry of these films have been determined by energy dispersive X-ray spectroscope （EDS） measurements. It is observed that the total luminescence intensity increases and the peak sits are strongly dependent on cerium concentration in the films. And the reason for the dependence is analyzed. It is proposed that the light emission observed generated by luminescent center associated with cerium chloride molecular rather than to atomic cerium impurities. The crystalline structure of the sample was analysed by X-ray diffractometry （XRD）. This luminescence feature has an advantage for display techniques, which require a purer blue emission.