以Y波导集成光学调制器保偏型干涉式光纤陀螺作为研究对象，根据各光学元器件的参数建立了各器件的琼斯矩阵以及光路传输模型，在此基础上进行了光路偏振误差的理论分析。通过推导，得到了保偏型干涉式光纤陀螺的偏振误差表达式，并首次分析了光源偏振度对光纤陀螺零漂的影响。借助光源尾纤输出的光谱，对由0%～3%之间呈线性变化的偏振度以及对经实验测试的光源偏振度的实际值引起的偏振模式耦合误差的零漂值进行了仿真计算。结果表明，当光路中其它参数不变时，由光源偏振度变化引起的零漂值为0．001°／h，满足了高精度光纤陀螺的精度要求。

Based on the polarization interference fiber optical gyroscope (IFOG) which uses Y waveguide integrated optical modulator,and according to the parameters of the optical instruments,their Jones matrixes and the mathematical model for the optical transmission of IFOG have been built. On this bases,the polarization errors are analyzed theoretically,the expressions of the polarization errors of IFOG are achieved,and for the first time,the influence of source degree of polarization on bias stability of IFOG is analyzed. In virtue of the source pigtail's output spectrum,the bias stability of polarization errors caused by the value changing linear between 0% ～3% and the test value of source degree of polarization are calculated by simulation. The result shows that bias stability caused by the changing of source degree of polarization is 0.001°/h,when other parameters are constant. This meets the requirements of high precision IFOG.