The photoluminescence excitation and emission spectra of Sr9Ga(PO4)(7) were investigated. This phosphor can be efficiently excited by VUV-UV light and X-ray irradiation and presents bright blue luminescence. The excitation and emission spectra of Sr9Ga(PO4)(7) were compared with those of ZnGa2O4 and Eu2+-doped (10 mol %) BaMgAl10O17. Under the same conditions, the light yield of X-ray excited luminescence of Sr9Ga(PO4)(7) is about 57% as large as that of scintillation crystal Bi4Ge3O12. The luminescence is suggested to be from the self-activation center of the octahedral Ga-O groups in the Sr9Ga(PO4)(7) lattices.