The invention discloses a graded positioning method for agricultural machinery navigation, comprising the following steps of acquiring a first positioning parameter, utilizing a Kalman filter to fuse the first positioning parameter, acquiring a second positioning parameter, acquiring a third positioning parameter, utilizing multi-sensor self-adaptive weighted fusion algorithm to fuse the second positioning parameter with the third positioning parameter, acquiring a target positioning parameter and positioning agricultural machinery according to the target positioning parameter. The invention also discloses a graded positioning system for agricultural machinery navigation. By fusing the positioning parameters acquired by measurement equipment for a plurality of times, the graded positioning method can smooth DGPS positioning data, effectively avoid the abnormal results of DGPS dynamic positioning, effectively filter test noise, reduce systematic error, form continuous, stable and accurate the information of the positions and course heading angles of agricultural machinery, and improve the positioning accuracy of agricultural machinery navigation.