The invention relates to an air-impact molding machine. The air-impact molding machine comprises a vertical post, a safety valve, a pressure gage, an airbag, an airbag air inlet, a piston rod, an air discharging valve, a valve disk, an air discharging channel, a residual sand frame, a sand box, a worktable, a lifting cylinder, a mold pulling cylinder and a flow divider, wherein the sealed airbag is fixed at the upper end of the vertical post; the safety valve and the pressure gage are respectively arranged on two sides of the top of the airbag; the airbag air inlet is formed in the middle of the airbag; the flow divider is arranged at the bottom of the airbag; the valve disk is arranged at the top of the flow divider and is connected with the flow divider through the air discharging channel; a guide post is arranged at the upper end of the valve disk; the mold pulling cylinder is fixed in a position under the flow divider at the bottom of the vertical post; the lifting cylinder is fixedly connected with the mold pulling cylinder; the worktable is mounted on the lifting cylinder; the sand box is arranged on the worktable; the residual sand frame is arranged in a position near the flow divider at the upper end of the sand box. The air-impact molding machine is simple, scientific and reasonable in overall structure, rapid and uniform in impact airflow, extremely high in sand mold compactability and high in productivity, and is suitable for large-scale production of casting workshops of small and medium-sized enterprises; the investment cost is reduced; and the pollution to the environment is alleviated.