A precise positioning method for peanut ellipsoid target with gravity center height compensation is proposed, which is suitable for field operation. This method optimizes the field calibration steps and completes the belt plane calibration with the help of self-made high-precision calibration block. The ellipse contour curve of peanut was fitted by the direct least square method, and the short half axis size was corrected again. The horizontal plane of the conveyor belt was taken as the reference, and the actual center of gravity of peanut was mapped to make positioning compensation. Grasping success rate increased from 87% to 97%. Field test shows that the positioning method has good industrial practicability which can meet the needs of actual production.