Abstract: In view of problem that existing drilling orientation device for drilling rig can not meet actual demand in terms of measurement accuracy, cost and operability, a drilling orientation device for drilling rig was designed which combines north-seeking system based on single-axis fiber optic gyroscope with tracking system based on micro-inertial measurement unit. Basic principle of north-seeking system was introduced taking four-position north-seeking method as an example, and various errors and their resources of the north-seeking system were introduced from aspects of output error of fiber optic gyroscope, installation error, inclination error, inversion error and geophysical quantity error. A nonlinear acceleration error compensation model was established for installation error and inclination error. Kalman filter method was used to correct random drift error of fiber optic gyroscope. The experimental results show that the reduction of inclination angle, random drift error of fiber optic gyroscope, mechanism rotation error and installation error can effectively improve north-seeking accuracy of drilling orientation device and meet drilling requirements of underground coal mine.