Abstract: Abstract: Sowing is a very important link in the process of agricultural production, and it is essential to make it timely, appropriate and meet agronomic environmental conditions according to the requirements of agricultural technology, so that crops can get a good foundation for growth. Precision planter for rapeseed can complete the ditching, stubble cleaning, rotary tillage, precision sowing, fertilization, soil covering and other operations, and it is widely used because of its high operating speed and high working efficiency. When the rapeseeds are sown, the flow process of rapeseeds is in a closed room, the color of rapeseed is similar with the color of soil, and the precision sowing index of rapeseed is mainly indirectly obtained through the change of the seed quantity in the seed box or through the speed of the seed metering device and the number of the type holes of the disks. Therefore, a set of sowing monitoring system for precision planter for rapeseed is designed to achieve sowing performance and sowing statistics in the process of rapeseed sowing. It is one of the trends to achieve transparency, informatization and intelligentization in sowing link. In recent years, many sowing monitoring systems for precision combined direct planter studied by experts at home and abroad were mainly used for the seed of large and medium size, such as corn and soybean. In this paper, the sowing monitoring system for precision combined direct planter is designed for rapeseed. The monitoring system is composed of multirow rapeseed flows sensing device and monitoring display terminal. Six rapeseed flow sensing devices are installed at the appropriate positions that are under 6 precision seeders on precision planter for rapeseed respectively to detect rapeseed flows. The weak voltage signals produced by rapeseed impacting on the piezoelectric film are processed by signal conditioning circuit, and then the seed pulse sequence corresponding to the seed flow is formed. Time capture interrupt program and timing counting program of MSP430F149 singlechip system in seed flow sensing device for rapeseed are used to record the metering time interval sequence of rapeseed flow, the metering frequency and the amount of metering, and the average time interval of seeding was calculated and used as the standard time interval of seeding. Through the national standard GB/T 6973-2005 (Testing methods of single seed drill (precision drill)), we got the leakage index and the qualified index of sowing. Then the data were sent to the sowing monitoring display terminal device wirelessly in "many to one" way, and the monitoring and display terminal single chip microcomputer system analyzed and processed the data and then displayed them through liquid crystal display screen in real time, including the multirow sowing monitoring and performance detection information and the sowing frequency curve for each row, so as to realize the real-time monitoring and the calculation of sowing quantity for precision planter for rapeseed. A polling data transfer protocol of response mode was designed to achieve reliability, fault tolerance and accuracy in data transmission, and the sowing monitoring system was tested. The results of bench test and field test of sowing monitoring system showed that the seeding monitoring system is stable and reliable, the monitoring accuracy of sowing quality is above 96%, and the data transmission is accurate, the transmission distance is about 60 m, which can meet the need of sowing monitoring, and provide effective technical support for the formation of sowing state diagram of rapeseed.