Abstract: Aiming at the problems of large size, high cost and blind spot of seeding performance monitoring sensor of pantoginseng precision seeder, a seeding performance monitoring device is designed in this paper. This device uses the refraction theory of light to combine fiber sensor and lens to expand the monitoring range of rectangular grating fiber sensor.The monitoring signal is transmitted to the PLC processor for statistics and processing of seeding performance, and the processing results are real-time human-machine interaction and fault acousto-optic alarm.The results of artificial seeding test and seeding machine test show that the accuracy of qualified rate monitoring is over 87%, and the alarm accuracy is high.The monitoring device can increase the monitoring range of the sensor, save the cost of the monitoring device, and provide a reference for the research on the monitoring technology of the precision seeder’s seeding performance.