（Gd_xM_yLu_0.99-x-y）₃Al₅O₁₂：1%Ce³⁺（x=0，0.01，0.25，0.5，0.75，y=0，0.005，0.01，0.02，0.05，0.1， M=Li⁺，Na⁺，K⁺，Cs⁺） series ceramic powders were synthesized by high temperature solid phase method. The microstructure of the sample was characterized by XRD， the excitation spectrum， emission spectrum and fluorescence lifetime of the sample were measured by FLS920 spectrometer， and the color coordinate of the sample was analyzed by the CIE chromaticity system. XRD results show that the Lu₃Al₅O₁₂ samples co-doped with different concentrations of alkali metal ions、Gd³⁺ and Ce³⁺ are still cubic crystal phases， but with the increase of alkali metal ions， Gd³⁺ and Ce³⁺ doping concentrations， the diffraction peaks of the samples shift slightly to a small angle. Under the excitation of 350 nm， compared with the Lu_2.97Al₅O₁₂：1%Ce³⁺ sample， the emission intensity of the sample co-doped with Gd³⁺ at around 511 nm decreased and appeared a significant red shift. With the increase of the doped Gd³⁺ concentration， the Ce³⁺ energy level lifetime gradually decreased. The range is 35~60 ns. Compared with the sample doped with 1%Ce³⁺ and 1%Gd³⁺， the luminescence intensity of the sample doped with 2%Li⁺， 2%Na⁺， 2%K⁺ and 1%Cs⁺ increased by 5.1 times and 2.93 times， respectively. At this time， the lifetime of Ce³⁺ in the sample continued to decrease. When the samples were irradiated under UV lamps with λ=254 nm and λ=365 nm， it was observed that with the increase of Gd³⁺ doping concentration， the color of the sample changed from dark yellow-green to dark red. The color coordinates show that the light-emitting area of the sample gradually moves from the yellow-green light area to the red light area. After co-doping with alkali metal ions， the sample emits brighter.