The invention discloses a medium-manganese high-silica low-fluorine smelting soldering flux, which belongs to the field of welding in the mechanical industry. The medium-manganese high-silica low-fluorine smelting soldering flux comprises the following effective compositions in portion by weight: 21 to 26 portions of MnO, 36 to 40 portions of SiO2, 4 to 8 portions of CaF2, 15 to 21 portions of CaO, 3 to 5 portions of TiO2, 3 to 5 portions of MgO, less than or equal to 8 portions of Al2O3, and less than or equal to 1.8 portions of FeO. The medium-manganese high-silica low-fluorine smelting soldering flux has the characteristics that poor manganese ore (namely low-grade manganese ore) can be utilized for production, the cost is low, the application scope is wide, various quality and technical indexes of the medium-manganese high-silica low-fluorine smelting soldering flux can meet the pertinent regulations of F4A2-H08A in the GB / T 5293-1999, and so on and the medium-manganese high-silica low-fluorine smelting soldering flux can be widely applied to union melt welding, semiautomatic welding, electroslag pressure welding, copper welding, pressure welding of vertical reinforcements and so on. in the process of equipment manufacturing in the fields of machine manufacturing, the petrochemical industry, coal metallurgy, mines, buildings, electric power, the military industry, aerospace, marine engineering, and so on.