In this paper, a long afterglow phosphor of LiGa5O8:Cr3+ was successfully synthesized by high-temperature solid-phase method. The phase composition, microscopic morphology and luminescence characteristics of phosphors are analyzed by X-ray diffraction scanning electron microscopy, transmission electron microscopy, fluorescence spectroscopy, Decay curves, and thermoluminescence curves. And discussed the kinetic series of LiGa5O8:Cr3+. Compared with phosphors with different Cr3+ doping concentrations, when the Cr3+ doping concentration is 0.5%, the sample has fewer impurity phases, high crystallinity, regular grain shapes, and a size of about 6 mu m. Fluorescence spectra show that the main excitation peaks are 398, 602 nm, and the main emission peak is 719 nm. Thermoluminescence spectra shows that the sample with 0.5% doping concentration has more effective traps and can store more that can produce long-lasting luminescence carriers, the kinetic order is 2 at this time.