Abstract: Ce³⁺:YAG phosphor thin films were deposited on quartz glass at room temperature by RF（Radio Frequency） magnetron sputtering technique in the pure argon atmosphere（3Pa） from Ce³⁺:YAG phosphor powder target.Subsequently annealed at 1100℃ for 3h in the nitrogen atmosphere.Visible upconversion luminescence was demonstrated in trivalent cerium doped YAG thin film(Ce³⁺:YAG) under focused infrared laser irradiation at 980 nm.The fluorescence spectra shows that the up-converted luminescences come from the 5d-4f transitions of the electrons in trivalent cerium ions.The linear relationship of luminescence intensity of trivalent cerium on infrared pumping power reveals that the conversions of infrared radiation are dominated by two-photon absorption process.