针对传统基于正弦波磁光调制的方位失调角测量系统存在测量精度不高的问题，提出了一种新的系统方位失调角测量模型以提高系统测量精度。通过分析传统的基于正弦波磁光调制的方位失调角测量原理发现，由于采用省略高阶项的贝塞尔函数展开式表示磁光调制后的信号，引入了信号截断误差和方法误差，影响了系统测量精度。在分析基础上推导建立了一种基于纯三角函数表示的无理论误差的方位失调角测量新模型并进行了仿真。仿真结果表明，利用推导建立的失调角测量新模型，系统测量精度明显高于传统方法，这对重新理解基于正弦波磁光调制的方位失调角测量系统原理、提高系统测量精度具有一定的参考意义。

To solve the problem that the measurement precision of traditional azimuth measurement system based on sine wave magneto-optic modulation polarized light is low, a new model of measuring azimuth is presented to improve the measurement precision. The principle of traditional azimuth measurement system based on sine wave magneto-optic modulation polarized light is analyzed. As the signal from modulator is expressed with the omitted high-order term Bessel function expansions, the method error and truncation error are detected. A new model which does not include theoretic error is presented, and the new model expressed in simplex trigonometric function is established. Simulation results show that the system measurement precision of the new model is obviously higher than the traditional one. It provides a certain reference to apprehend the system principle and improve the system measurement precision.