Abstract: Arming at loss sowing phenomenon for Giant Juncao planter and in order to improve quality and anautomation level of seeding machine，a type of leakage seeding system based on STM32 was proposed.System used photoelectric sensor to monitor leakage seeding and used encoder to meter seed sowing device’s speed.When monitoring miss seeding，microcomputer would drive step motor to carry out action of resowing.If planter encounters a unsolvable problem，system would give a alarm.To verify reliability of system，a prototype with sowing resow system was tested.And test results showed that when seeding rate at 1～6 km/h，seed leakage rate was low and resowing rate was high，which greatly improve seeding quality of Giant Juncao planter.