Position and azimuth determining system of ring laser gyroscope (RLG) is useful for improving survival capacity,mobility and operational capacity of army.In order to take full advantage of quickness,maneuverability and accuracy of the system,starting from the working mode,the theory of ZUPT,error factors and the application conditions of different working modes were analyzed.The mechanism of working modes was discussed and contrastive test was carried out.The experimental results show the validity of theoretical analysis,which provide valid reference for operation and maintenance of position and azimuth determining system.