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　by　three　different　cooling　ways,　including　air　cooling,　water　cooling　and　liquid　nitrogen　cooling.　Combined　with　different　test　methods　such　as　XRD,　SEM,　IR,　the　influence　of　cooling　ways　on　the　structure　and　hydraulic　activity　of　blast　furnace　slag　was　studied　in　the　present　in　investigation.　The　relationship　between　glass　content,　compressive　strength　and　the　phase　compositions　of　blast　furnace　slag　has　been　obtained.　The　results　showed　that,　the　glass　content　of　water　cooling　slag　or　liquid　nitrogen　cooling　slag　was　slightly　higher　than　that　of　air　cooling　slag,　there　was　obviously　gehlenite　crystal　phase　in　air　cooling　slag.　The　7d　and　28d　compressive　strength　of　three　slags　did　not　present　positive　correlation　with　vitreous　content,　the　sequence　of　28d　compressive　strength　of　three　slags　was　water　cooling　slag　＞　air　cooling　slag　＞　liquid　nitrogen　cooling　slag.　SEM　observation　found　that　crystallization　phases　in　water　cooling　slag　had　a　small　grain　and　uniform　distribution,　this　kind　of　structure　was　advantageous　to　the　latter　hydration　reaction　and　strength　development　of　blast　furnace　slag.　©　(2015)　Trans　Tech　Publications,　Switzerland.