95%。The control technique of variable rate fertilization is introduced. Using single chip microcomputer as CPU, a control system of variable rate fertilization was designed, including force sensor, AD data acquisition system and servo-actuator. An assorted software was designed for selecting data and sending commands. Through test-bed experiment and analysis, the system can complete the control of variable rate fertilization, which has a simple structure, stable operation and high , fertilization precision up to 95%.