Abstract: Abstract: The loss sowing phenomenon is common for sowers for crops with large grain. Reseeding and seed-metering devices now available are independent of each other. This method has some problems such as reseeding inaccurately. In order to solve these problems, an automatic reseeding method based on an overrunning clutch was proposed in this paper. An automatic reseeding device that was composed of both a reseeding device and a seed-metering device was designed. The device adopted a hall sensor to get the speed of the seed-metering device. The hall sensor got the time interval between every two seed spoons of the seed-metering device to calculate the real-time speed of the seed-metering device. A laser sensor was used to monitor the loss of seeds. Seeds in the plate of the seed-metering device could block the light propagation path of the laser. If the light propagation path of the laser was not blocked, the seed was lost. An overrunning clutch was used to connect a step motor and the axle of the seed-metering device. The step motor was used to drive the seed-metering device to reseed with high speed. The overrunning clutch is a kind of compound function bearing which transmits torque between the inside hub and outside hub in one direction and allows free overrun in the opposite direction. It was used to switch torque source between the wheels of the seed-metering device and the step motor. The torque source came from the wheels of the seed-metering device when seeding but from the step motor when reseeding. When the laser sensor monitored the loss of seeds, the controller calculated the rotational speed and angle of the step motor based on the real-time speed of seeding and position of the missing seeds. The step motor drove the seed-metering device to reseed with a higher speed than seeding speed. The subsequent seed was added to the vacant position quickly. The system of the automatic reseeding device would give failure warnings to the user if the seed-metering device has a breakdown. Experiments show that when the seeding speed is between 2 km/h and 5 km/h and the continuous missing seeds number is less than 3, the error of the reseeding time interval increases as the seeding speed and the continuous missing seeds number increase. However, the maximum relative error of the reseeding time interval is less than 1.37%. The automatic reseeding device has a good performance of reseeding timeliness. The failure warning system of the automatic reseeding device can warn users of the failure of the seed-metering device accurately. The accuracy of the failure warning is 100%. The qualified index of seeding space is 100%. The variation rate of seeding space is 14.48%. Both of the qualified index of seed space and the variation rate of seed space are much better than the performance indicators of precision seeders in Chinese standard. The reseeding accuracy of the automatic reseeding device is high. The average rate of successful reseeding is 92.98%, the comprehensive missing rate decreases to 0.8%, and the sowing rate increases to 99.2%. The automatic reseeding device has a good effect. The study can provide a reference to improve the design of the precise seeder for large grains.