Abstract: Abstract: Precision seeding machine has been widely used in recent years. There are still some mechanical failures with the machine. And seeding stoppage caused by the field environment will appear during seeding with machine. So, it is essential to monitor the seeding quality. With the research of monitoring technology, visual instrument detection system for precision seeding-metering device is used in laboratory but not suitable in the field. Image processing technology is efficient and accurate but complex and high-cost. The photoelectric inspection technology is low-cost, reliable and quite accurate. First of all, we introduced the theory of the monitoring technology with the infrared detection, which is a common photoelectric inspection technology. We designed a kind of opposite-type photoelectric sensor. Transmitter using the infrared LED (light emitting diode) gave the infrared signal to receiver. The signal had narrow band and directivity when the receiver LED was sensitive to prevent the interference of the visible light and the dirt. The photo diode of receiver was matched with the transmitter, and the power of the signal was measured to detect the passing seeds. When there was a seed between the transmitter and receiver, the infrared signal may be kept out by the seed. Therefor, the power of the signal was getting weak, and the seed was detected. There was a differential circuit after the receiver processed the signal received. The circuit formed a pulse signal which was sent to the micro processer to count the passing seeds. The time of pulse was 0.4 to 4 ms. It had adequate resolution to distinguish adjacent seeds. Then with the theory of the monitoring technology, we developed the seeding quality monitoring system, including the multiplex sensors, the driver gear sensor, and the terminal device with LCD (liquid crystal display) and alarm. We designed a kind of structure to fix the sensor with the tube, and aligned the transmitter with the receiver. The driver gear sensor was used to detect the drive shaft of the seeding apparatus. When it detected the seeder is seeding, the alarm would be available, and it would be triggered if there was no pulse signal of seeding to the processer. It could help to avoid false alarm when the seeder is not seeding. The processer could count and make statistic of the seeding quality, and display the result on the LCD. The monitoring system is reasonable in structure, convenient to install, and will give an alarm signal when seeding is blocked, leaked, lacking seeds or in other stoppage. At the meantime, the system counts and displays the number of seeding and the stoppage caused by different reasons. At last the paper introduced the field test results. Field experiments were carried out to measure the count of seeding, the leakage seeding rate, the lack of seed and the blockage of the seeding tube. It showed that the monitoring system could adapt to the working environment. The field test presented a monitoring success rate of more than 95%. Shooting the trouble of on-line monitoring of seeding quality, the system avoids miss-seeding, performs the efficient seeding and improves the seeding quality.