An intelligent path tracking control method is proposed based on fuzzy immune PID (proportional-integraldifferential), to realize path tracking control for small agricultural machinery in complex environment. Firstly, a path tracking control task is decomposed into linear automatic navigation control task and automatic steering control task, and a fuzzy controller for automatic navigation and an automatic steering control method based on fuzzy immune PID are constructed. An automatic navigation control system is developed with dual laser source localization technology, electronic compass and angle sensor based on the hardware system of the unmanned high speed transplanter. Secondly, the straight line and the curve line path tracking methods are proposed based on the machinery construction and working principle of the automatic navigation control system. At last, the effectiveness of the path tracking control principle and fuzzy controller design is verified by using Matlab/Simulink simulation platform and the transplanter kinematics model, and the straight line and the curve line path tracking experiments are also completed. When a transplanter makes the linear tracking at 1 m/s, the maximum deviation is only 4 cm, and the average tracking error is 0.84 cm; when it makes the curve line path tracking at the same speed, the maximum deviation is 0.6 m, and the average tracking error is within 12 cm. Simulation and experiment results show that the unmanned high-speed transplanter based on this control system can effectively track the predefined path.