A system includes a hollow shaft, a drum, an absolute encoder, a driving mechanism, a conveyor belt, a photoelectric sensor, and a controller. A structural optimization design method of the drum is provided on the basis of theoretical calculation of a seeding track of the drum-type seed-metering device, a theoretical model of a conveying position of a tray and a seed-metering angle is built with the aim of continuously sowing grains to the center of each hole, the conveying position of the tray and a rotating position of suction holes on the drum are monitored in real time on a seedling raising line, and a difference value between the actual position of the suction holes and the theoretical seed-metering angle and a change rate of the difference value are calculated and serve as input parameters to design a fuzzy controller of the rotation speed of the drum.