Abstract: Ferromanganese ore is an important raw material for manganese and iron beneficiation and smelting. It is difficult to separate manganese and iron efficiently due to factors such as isomorphism and fine particle embedding. Thetechnological process of hydrogen based mineral phase transformation magnetic separation was established for high silicon ferromanganese ores, and the effects of roasting temperature, roasting time, reduction gas concentration and total gas volume on the separation of ferromanganese and the conversion rate of manganese divalent were investigated. The experimental results show that under the conditions of grinding fineness of −0.074 mm accounting for 72%, roasting temperature of 660 ℃, gas volume ratio CO: H₂=1:3, reducing gas volume concentration of 50%, total gas volume of 600 mL/min, roasting time of 40 minutes, magnetic separation magnetic field strength of 1070 Oe, a manganese concentrate with a total manganese grade of 31.00%, a recovery rate of 91.01%, a divalent manganese conversion rate of 91.29%, and an iron concentrate with an iron grade of 28.50% and a recovery rate of 50.63% can be obtained. The results of chemical composition analysis, XRD analysis and SEM−EDS analysis show that manganese minerals and iron minerals have been effectively separated.