An automatic discharge hopper, comprising a main body (1) having an open structure at a lower end, and provided with a discharge plate (2) therebelow. The discharge plate (2) is pivoted to a lower terminal portion of the main body. The main body is symmetrically provided with two pneumatic cylinders (3). Piston rods of the pneumatic cylinders are pivoted to the discharge plate. A curved protrusion (21) is provided on the side of the discharge plate facing the main body. A pressure sensor used to detect a pressure on the discharge plate is mounted on the main body. When the pressure on the discharge plate reaches a preset pressure value, the piston rods of the pneumatic cylinders extend downward and drive the discharge plate to be inclined downward at a preset slope. In addition, the side of the main body facing the discharge plate is provided with the curved protrusion. In this way, the present invention enables a smooth discharge of a powder material, and achieves a rapid and automatic discharge of the material, thus saving manual labors, and improving operation efficiency.