Abstract: To improve the reliablity of the seeding performance of corn planter, a monitoring system was developed based on capacitive sensor. In order to obtain constrained conditions of the electrode plate length, corn seed movement discipline and mechanism in the dropping process were analyzed theoretically. The detection circuits mainly consisted of microcomputer PIC18F2580, capacitive convert chip MS3110 and AD7685. The capacitive pluse peaks interval and curve integral were calculated, the information of seeding performance were obtained such as seeding quantity, missing rate and multiples rate. The experiment results showed that the system accuracy for single seed detection was up to 97.3%, and when the simulation velocity of the planter was 4.0 km/h, the system had an accuracy of 94.6% in seeding quantity, 93.5% in missing detection and 88.1% in multiples rate. This system can effectively monitor seeding performance and help to improve sowing quality.