Using　the　industrial　limestone,　fly　ash　and　pure　chemical　reagents　as　raw　materials,　the　blast　furnace　slag　was　prepared　in　the　simulation　condition　of　the　actual　slag-making　process.　Using　uniform　design　method,　the　influence　of　blast　furnace　slag　composition　factors　such　as　quaternary　alkalinity,　ratio　of　CaO/MgO　and　ratio　of　SiO2/Al2O3　on　the　glass　content　of　blast　furnace　slag　were　studied　in　the　present　in　investigation,　the　relationship　between　glass　content　and　the　various　factors　has　been　obtained　through　regression　analysis,　and　the　main　influence　factors　and　the　optimum　blast　furnace　slag　compositions　been　found　out.　The　results　showed　that,　the　impact　of　various　factors　on　the　glass　content　of　granulated　blast　furnace　slag　was　quaternary　alkalinity　＞　ratio　of　SiO2/Al2O3　＞　ratio　of　CaO/MgO.　According　to　the　significance　test　of　the　regression　equation　and　the　verification　experiment,　it　was　concluded　that　the　optimum　compositions　of　granulated　blast　furnace　slag　were:　the　quaternary　alkalinity　was　0.85,　the　ratios　of　CaO/MgO　and　SiO2/Al2O3　were　11.5　and　6.5　respectively,　and　in　this　condition,　the　glass　content　of　granulated　blast　furnace　slag　reached　to　98.47%.