Dumping　the　slag　into　vertical　mill,　granulated　blast　furnace　slag　powder　is　finally　got　by　the　crushing,　grinding　and　separation　in　the　vertical　mill.　The　whole　process　is　a　non-linear,　multivariate　process.　In　this　process,　maintaining　the　stability　of　material　layer　thickness　can　reduce　the　mill　vibration　and　power　consumption.　So　this　paper　analyzed　the　slag　powder　production　process　firstly.　Then　the　models　of　material　layer　thickness,　production　and　specific　surface　area　are　established　based　on　the　field　data　by　using　least　square　support　vector　machine　(LSSVM).　Finally　the　suitable　range　of　material　layer　thickness　is　obtained　by　multi-objective　optimization　of　production　and　specific　surface　area.　©　2018　IEEE.