A method of updating an all-attitude angle of an agricultural machine based on a nine-axis MEMS sensor includes the following steps: establishing an error model of a gyroscope, an electronic compass calibration ellipse model and a seven-dimensional EKF filtering model, and setting a parameter vector corresponding to a vehicle motional attitude (S1)； acquiring data including an acceleration and an angular velocity of a motion of vehicle, and an geomagnetic field intensity in real time (S2)； calculating an angle, a velocity, position information, and a course angle of the vehicle by established error model of the gyroscope and the electronic compass calibration ellipse model(S3)； data-fusion processing the angle, the velocity, the position information and the course angle of the vehicle by the seven-dimensional EKF filtering model, and updating a motional attitude angle of the vehicle in real time. The steps of the method have a small error, high precision, and reliability.
