The　composition　and　structure　of　blast　furnace　slag　have　influence　on　its　early　hydration　characteristics.　In　this　paper,　various　blast　furnace　slag　with　different　chemical　composition　and　structure　were　studied　by　means　of　X-ray　diffraction,　ICP-MS　spectroscopy　and　29Si　MAS　NMR　to　research　the　relationship　among　glass　phase　polymerization　state　with　the　ion　dissolution　characteristic　in　alkaline　environment,　and　the　change　of　silicate　tetrahedron　polymerization　state　with　hydration　age.　The　results　showed　that　the　structure　of　glass　phase　was　affected　by　chemical　composition　and　content　of　crystalline　phase　in　which　the　existence　and　increase　of　crystalline　phase　and　Al-O　structure　unit　could　reduce　the　degree　of　polymerization.　In　the　glass　phase　network　structure,　the　network　modifier　was　inhomogeneously　distributed　among　the　networks,　and　the　hydrolysis　of　the　different　structural　units　would　be　accompanied　by　different　hydration　characteristics.　In　alkaline　environment,　the　more　Si-O　structure　units　in　glass　phase,　the　structure　of　Si-O　was　more　easily　hydrated,　resulting　in　higher　concentration　of　silicon　ions　in　the　solution,　and　more　exist　of　polymeric　silicate　tetrahedrons　in　the　gel　products,　and　the　pH　value　of　environment　was　obviously　decreased.　With　the　more　exist　of　more　Al-O　structure　units,　the　structure　of　Al-O　was　more　easily　hydrated,　resulting　in　higher　concentration　of　aluminum　ion　and　calcium　ion　in　the　environment,　which　corresponding　to　only　a　small　amount　of　highly　polymeric　Si-O　tetrahedron　could　be　distinguished　in　the　gels,　and　the　hydration　process　could　keep　at　a　high　pH　value.　©　2018,　Materials　Review　Magazine.　All　right　reserved.