Compared with the north seeking schemes under the static condition,the dynamic north seeking schemes can effectively restrain the random errors of the Fiber Optic Gyroscope (FOG),and greatly improve the accuracy and rapidity.Least square fitting method,mathematical function modulation/demodulation method and unit function modulation/demodulation method are common dynamic north seeking algorithms.In the paper,the principle of least square fitting algorithm is introduced and related formulas are deduced.Two north seeking models are established by Matlab/ Simulink simulation tool and the applicability of the model is tested.The effects of rotation speed,sampling frequency,random errors,sampling points and constant drift on the dynamic north seeking result of FOG are studied by the established models.The simulation results show that the random drift noise is the key factor that affects the accuracy of the north seeking,and other factors also restrict the accuracy of the north seeking.The effect of sampling points on the results of the north seeking shows that the north seeking errors tend to be stable when sampling points are enough,and north seeking can be realized with the residual period sampling and north seeking time can be shortened.