Polar navigation ship strapdown inertial navigation system readjusting method based on horizontal coordinate system

The invention provides a polar navigation ship strapdown inertial navigation system readjusting method based on a horizontal coordinate system. The method comprises the steps of acquiring a horizontal longitude position error and a horizontal latitude position error at tn moment, and readjusting the system position error to obtain the relationships between the latitude and longitude position errors and a platform drift angle at the tn moment as well as between a course error and the platform drift angle at the tn moment; re-observing at t[n+1] moment, acquiring the horizontal longitude position error and the horizontal latitude position error of the second point, and readjusting the system position error to obtain the relationship between the position course error at the t[n+1] moment and the gyroscopic drift; observing at t[n+2] moment thirdly, and acquiring the horizontal longitude position error and the horizontal latitude position error of the third point to obtain the relationship between the position co