The key of improving the transmission stability of the light wave phase difference in the optical path of the optical voltage sensor is the suppression of the parasitic interference phase difference of the system optical path. To this end, an optical voltage sensor based on the Pockels effect of crystal material and combined with the sagnac optical path structure is studied. Based on the analysis of the reciprocity mechanism of the optical path structure, it is proposed to change the system optical path to use panda-type polarization maintaining fiber and low the combined form of the birefringent rotating fiber can eliminate the mode phase difference generated by the light-sensitive circuit section, thereby improving the optical reciprocity of the sensor. A mathematical model of the temperature field and thermal stress of the optical path of the system is established, and the influence of the external environment temperature on its phase difference propagation is studied by finite element simulation. It is obtained that for every 1℃ increase in the external temperature, the optical path birefringence decreases by 2. 275 21×10 -7 on average. Based on this, an experimental study on the reciprocity optical path has been carried out, and experiment shows that the maximum influence of temperature on the measurement result is 1. 733 9% / ℃ . When the ambient temperature rises by 10℃ , compared to the optical path, all panda-type polarization-maintaining fibers are used for sensor measurement. The accuracy is increased from 6. 008% to 1. 53% ; when the temperature rises by 20℃ , the accuracy is increased from 52. 016% to 8. 13% . The feasibility of the reciprocal optical path can be preliminarily proved.