In order to provide a theoretical basis for the measurement deviation of reflective all fiber current transformer(optical CT), the influence mechanism of the main optical components of reflective optical CT system on the system response is studied, and the influence of the non ideality of the main optical components of optical CT on the accuracy of current measurement is analyzed. Firstly, the main devices and mathematical models of the system are described by Jones matrix, and the expression of the output light of the system and the measured value of the injection current of the system after demodulation and detection are given. Then, based on the system mathematical model, the effects of the linear birefringence and circular birefringence of the sensing fiber and the linear birefringence of the polarization maintaining fiber on the injection current measurement of optical CT are analyzed respectively. The results show that the linear birefringence deviation of sensing fiber has the most prominent influence on the measurement accuracy of optical CT injection current. The circular birefringence of sensing fiber can effectively suppress the influence of linear birefringence of sensing fiber on the measurement accuracy of optical CT injection current.