Abstract: In order to support the large-scale transformation of intelligent efficiency improvement of Nanfen Concentrator，taking the ore in the main stope as the research object，and on the basis of process mineralogy research，the combined process flow of dry tailings discarding before roller grinding-high pressure grinding roller-wet tailings discarding of roller grinding products-stage grinding-low intensity magnetic separation can be used to remove the tailings with yield of 21.40% in advance，greatly reduce the subsequent grinding amount，and improve the TFe grade of the ore entering the grinding process. The final yield of iron concentrate is 39.07%，the content of TFe and mFe are 68.20% and 66.19% respectively，and the recoveries of TFe and mFe are 86.66% and 98.98% respectively.

Key words: magnetite, high pressure roller mill, stage grinding, low intensity magnetic separation