Pneumatic cylinder-type seed-metering device

The invention discloses a pneumatic cylinder-type seed-metering device. The device comprises a frame, a roller and a seed box. The cylinder has a hollow structure, through holes are opened on the surface of the cylinder, and the size of the through hole is smaller than the size of the seed; the cylinder is rotatably installed on the frame, and a discharge port of the seed box is slantly abutted to the surface of external circumference of the cylinder; a ventilation panel is fixedly installed on the frame, one end of the cylinder is rotatably sleeved on the ventilation panel, the inner part of the cylinder is provided with a separation apparatus, the separation apparatus is fixedly connected to the ventilation panel, the internal space of the cylinder is divided into two sealed areas, and the two sealed areas respectively communicate with an air inlet and an air outlet of the ventilation panel. Seeds in the negative pressure area on the surface of the cylinder are adsorbed and stuck on the through holes, when