Fluorescence　material　of　Sm　doped　Si-Ca-Mg　system　was　synthesized　by　using　the　method　of　solid　phase　reaction　at　high　temperature.　The　phase　composition　and　crystal　structure　of　this　material　were　analyzed　with　XRD　method　for　its　composition　and　the　existence　form　of　Sm　atom.　We　aimed　to　exactly　determine　the　phase　composition　of　this　fluorescence　material　and　the　doping　position　and　environment　of　rare-earth　Sin　atom　in　the　system　because　these　factors　have　significant　effects　on　the　properties.　The　analytical　results　show　that　the　Sm　atoms　dope　in　Ca2O26Si6Sm8　lattice　in　the　form　of　atomic　site-occupation　in　three　different　space　positions　with　different　occupancy　rates.　Therefore,　based　on　the　XRD　analytical　results,　the　fluorescence　material　of　Sm.　doped　Si-Ca-Mg　system　with　high　performance　can　be　synthesized.