The　slag　obtained　in　the　process　of　pig　iron　smelting　has　been　widely　used,　but　the　variational　hydration　activity　always　is　a　significant　factor　affecting　its　quality.　In　this　experiment,　the　laboratory　simulated　slag　was　prepared　by　adjusting　the　chemical　composition　and　cooling　method.　The　experiment　primary　characterized　the　structure　and　hydration　process　with　different　types　of　slag　by　using　MAS　NMR,　XRD,　compressive　strength,　ICP,　SEM,　and　hydration　heat,　then　obtained　the　influence　of　the　composition　of　the　network　former　S/A　(the　mass　ratio　of　SiO2　and　Al2O3　in　chemical　composition)　and　amorphous　phase　content　on　its　structure　and　hydration　activity.　The　result　shows　that　lowering　the　S/A　value　can　reduce　the　degree　of　vitreous　polymerization　in　the　slag;　reducing　the　S/A　value　of　the　slag　can　make　the　slag　hydration　time　advance,　and　consequently,　the　cumulative　exotherm　increases,　the　liquid　phase　Ca/Si　and　Al/Si　ionic　ratio　increases,　and　the　hydration　product　changes　from　C-S-H　gel　to　C-A-S-H　gel,　which　ultimately　leads　to　an　increase　in　compressive　strength.　In　the　high　S/A　value　slag,　the　formation　of　the　trace　crystal　phase　of　gehlenite　is　beneficial　to　reduce　the　degree　of　polymerization　of　the　amorphous.