An automatic calibration method of an angle sensor for an automatic drive control system of a farm machine includes the following steps. Step S1: Step S1: fixing a steering wheel of the farm machine to make front wheels of a vehicle kept at a fixed angle. Step S2: collecting a plurality of pieces of current position information of the farm machine, and processing the plurality of pieces of current position information to obtain an average value. Step S3: establishing a two-wheel farm machine kinematics model based on a center of a rear axle. Step S4: performing a radius calculation to obtain a set of angle correspondences. Step S5: rotating the farm machine by a preset angle at a constant speed with the rear axle of the farm machine as a center, and performing Step S1 through Step S4；Step S6: after performing Step S5 for several times, performing an angle value fitting calculation to obtain a calibration coefficient. By applying the technique combining vehicle kinematics and high-precision GNSS, a high-precision angle sensor calibration can be realized without the external assisting apparatus and related experiential parameter input, and an automatic calibration can be realized. The present application is suitable for the precise agricultural automatic drive control systems.
