The current corn sowing depth is controlled by limit wheels and profiling mechanism that can only achieve the consistency of ditch depth and can not achieve the consistency of sowing depth. From the view of soil cover and compaction soil determining the thickness of the upper soil(sowing depth), the author developed covercompaction soil monitoring system that can achieve automatic control of planting depth, ensure the consistency of corn planting depth, and establish the basement of the neat, complement, sturdy of the seedling. The system took MSP430 microcontroller as control center, expert system shaped from compaction strength by field experiment as standard, result from pressure transmitter of compaction soil system as a means, to realize the results from transmitter contrasting with the expert system. Then the machine can constantly adjust the cover soil system and the amount of overburden soil to ensure the stability and consistency of sowing depth and compaction strength. The working principle of covercompaction soil control system is that when machine worked the pressure transmitter which was arranged on compaction wheel, it can constantly detect the pressure of the wheel, then the pressure data was imported to microcontroller memory and compared with the threshold which was arranged in expert system. If the data was within the range of the threshold, the sowing depth will be normal and the system will maintain the status quo. If the data was higher than the threshold,the sowing depth and compaction strength would be too large, it meant that the machine should reduce the sowing depth, then the microcontroller will send message to shorten the electric cylinder’s length until the data under the standard value in order to reduce the amount of the overburden soil and vice versa. The author conducted response time experiment and the result indicated that the response time of the system was 0.58s and the actual response time was less than the experiment. Field experiment results showed that when machine’s sowing speed reached from 3km/h to 8km/h, the qualified rate of sowing depth was higher than 90% and the sowing quality was better than that of profiling mechanism device, so the system effectively improved the consistency of sowing depth.