La3Ga5SiO14 (LGS) thin films were grown on (200)-textured MgO buffer layer, which was deposited on the silicon wafer, by sputtering at 600°C. These thin films were annealed and transformed form amorphous to the LGS crystalline phase with the heat treatment temperature higher than 1150°C. It was found that the films with LGS crystalline phase showed luminescent characterization whereas the LGS sintered solids did not. The emission peak of the films was found to be 438 nm under the excited light of λex=300nm. Effects of annealed temperature on the luminescent properties of the thin films are investigated. The relationship between the mechanism of luminescence and the crystalline structure of the LGS films are discussed.