The utility model discloses a diaphragm molding device, which comprises a gas hood, a water flow plate, an inductive iron plate, a support frame and electromagnetic coil, wherein both the water flow plate and the inductive iron plate are fixed on the support frame; the gas hood is covered above the water flow plate; the side part of the gas hood is provided with a gas vent; the gas vent is communicated with the cavity of the gas hood; the top surface of the water flow plate is provided with a plurality of diaphragm molds; a water flow hole is formed in the water flow plate; both the water inlet and the water outlet of the water flow hole are connected with a water flow pipe; and the electromagnetic coil is arranged on the lower part of the inductive iron plate. The diaphragm molding device has high molding efficiency and low power consumption.