The utility model discloses an upper discharging opening chute of a sieving machine. According to the upper discharging opening chute of the sieving machine, the service life of a conveying belt can be effectively prolonged and flying dust can be effectively reduced. The upper discharging opening chute is a rectangular box body, wherein a material inlet is formed in the place, close to a discharging opening of the sieving machine, on the top surface of the box body; a material outlet is formed in the place, far away from the discharging opening of the sieving machine, on the bottom surface of the box body; the bottom surface of the box body and the side wall of the box body form a material buffering area. Due to the fact that the upper discharging opening chute is of a box body structure, and the material buffering area can be formed on the bottom surface during use, a material is prevented from directly impacting the conveying belt, the impact on the surface of the conveying belt is reduced, and the service life of the conveying belt is prolonged; meanwhile, due to the fact that the upper discharging opening chute can effectively isolate the flying dust generated by mutual impact and friction among materials in a material falling process, most of flying dust is sealed in the box body, the flying dust in the field is reduced, and the working environment of the field is effectively improved.