Abstract: The blue-emitting phosphor MGa₂S₄:Ce(M=Ca, Sr) was prepared, and its crystallinity wasanalysed by X-ray diffraction. The excitation and emission spectra of MGa₂S₄:Ce were measuredand investigated, and the effects of the cerium concentration and the composition of host materialon the PL properties for MGa₂S₄:Ce powder were studied. The results of PL measurement showedthat MGa₂S₄:Ce phosphor achieved an even more saturated blue emission, and the optimumcerium concentration for high efficiency and more saturatated blue emission was sbout 6mol% for MGa₂S₄:Ce, 3～4mol％ for SrGa₂S₄:Ce