Abstract: Aiming at the problems of poor adaptability, large variation of plant spacing, high missed sowing rate and damaged potato rate of the existing potato planter in sowing operation, the missed sowing monitoring system of potato planter with AT89S51 as the control core is studied. The system is composed of trigger and infrared monitoring modules. The trigger module is composed of small magnetic steel and Hall sensor. When the small magnetic steel is close to the hall sensor, The system will trigger and start the potato missing sowing monitoring system composed of infrared transmitting and receiving modules. The system is installed on the monitoring points of the main sowing spoon chain and the supplementary potato spoon chain at the same time. If the infrared monitoring system finds that there is no seed potato in either of the main spoon chain and the supplementary potato spoon chain, it will immediately drive the stepping motor to realize rapid supplementary potato. The potato supplement mechanism is composed of a single row double chain spoon chain seed taking mechanism, in which the seed taking spoon chain is divided into the main seed spoon chain and the potato supplement spoon chain. The main seed spoon chain is driven by the land wheel, and the potato supplement spoon chain is driven by the stepping motor. The two sowing chains share a lower potato mouth to ensure the same plant spacing, When the missing seeding monitoring system monitors that there is no seed potato in the anchor seed spoon chain, it will immediately drive the stepping motor to drive the potato supplement spoon chain to realize accurate potato supplement. The test shows that when the working linear speed of spoon chain is 0.4～0.7m/s, the success rate of potato supplement is 85% ～ 87% and the total success rate of sowing is 99%, which solves the operating performance of potato planter well, and the working linear speed of spoon chain seed taking mechanism studied in this paper is higher than that of spoon chain studied by predecessors.