In hybrid current fiber sensors operating on the Faraday effect, reflection ig often used for changing the propagating direction of light to increase the effective optical path and to make the structure of the sensos compact. But the reflection changes the polarization of light, and consequently have an effect on the sensor's sensitivity. In this paper, Jones matrix method is used to derive the propagating characteristics of the sensor. The effect of reflection on sensor's sansitivity has been analysed and the results obtained agree with experimental data.