This invention discloses a sort of combination orientation method of farm-machinery guidance. This method adopts the pseudo-distance difference GPS sensor to progress measure and receives abecedarian orientation position figures of the farm-machinery. Then it uses the electron box-needle and the micromachining peg-top sensor to progress measure to course angle of the farm-machinery, it progress weighting amalgamation by the self-adapting, and it obtain the best course angle figures. It adopt the self-adapting Kallman filter to progress amalgamation again to the polygenetic information of the abecedarian orientation position figures and the course angle figures, accordingly it can obtain accurate estimate of the farm-machinery orientation and the course angle information. This invention provides more accurate and accurate reckon data of the course angle; the orientation can be controlled in the GARMIN extent, and can form the continuous and steady navigation data of farm-machinery.