The invention relates to the technical field of flanges, and discloses a flange fixing device utilizing a lever transmission principle for dual fixing. The flange fixing device comprises a supportingseat, the supporting seat is internally and movably connected with gear columns, the gear columns are externally connected with inner arc-shaped toothed rods and outer arc-shaped toothed rods in a meshed mode, the inner arc-shaped toothed rods are externally connected with first pull rods in a hinged mode, the outer arc-shaped toothed rods are externally connected with second pull rods in a hingedmode, and the first pull rods and the second pull rods are externally connected with sliding rods in a hinged mode. Through cooperative use of the gear columns, the inner arc-shaped toothed rods, theouter arc-shaped toothed rods, the first pull rods, the second pull rods and the sliding rods, the effects of adjusting the sliding rods and enabling the sliding rods to drive fastening blocks to clamp flanges are achieved, clamping of flanges with different diameters can be achieved, so that the number of clamps is reduced, then the flange production cost is reduced, the clamp storage space is reduced, meanwhile, the axes of the flanges can be determined, the axes of the flanges and the axis of the supporting seat are collinear, and then the flange machining precision is guaranteed.