The pendulous gyro north-seeker has strict requirement to its initial erection azimuth, and it is difficult to implement omni-bearing north seeking. Taking a certain type of pendulous gyro theodolite as prototype, we established the motion equation of pendulous gyro in large azimuth by using Euler dynamical equations, deduced the mathematical model of gyroscope motion and the trajectory of gyroscope sensitive department, and proposed an improved rough north-seeking method for large azimuth, called tracking speed detection method. Experiments were designed and conducted to verify the new method. The analysis and experiment results show that the proposed method can achieve omni-directional north seeking at any initial erecting azimuth within 1 minute, and the maximum azimuth of the basic shaft of the gyro is about 6°. The new method is of great importance for realizing all-directional orientation of the pendulous gyro north seeker.