Abstract: A north-finding commander sight for tank and armored vehicle was designed. It adopted two fiber optic gyros and two accelerometers to realize inertial measurement and gyro information was shared by both north finding and line of sight (LOS) stabilization. The control process and combined algorithms were designed. While ensuring a high accuracy of the commander sight LOS stabilization, it performed north finding in any position when the vehicle azimuth platform was unleveled. The north-finding method was that the commander sight rotated to four fixed positions and stopped for an interval at these positions, these intervals are used to sample and store data at the four positions. After the completion of four-position rotation, the recorded data were combined, filtered and calculated to obtain the north-finding result. The concept design, implementation approach and derivation approach were discussed. The demonstration test proves that the desired specifications are achieved.