Optical voltage sensors(OVS) represent the developmental direction of next-generation voltage transformers. The primary challenge currently facing OVS is the ineffective resolution of linear birefringence in electro-optic crystals induced by temperature drift, which has become a bottleneck restricting their practical application. To address this issue, this paper proposes a dynamic decoupling and compensation method for linear birefringence in OVS electro-optic crystals under the influence of temperature drift. First, a mathematical model characterizing the linear birefringence of bismuth germanate oxide(BGO) crystals is established based on the crystal′s optical indicatrix equation. The generation mechanism and dynamic characteristics of linear birefringence and electro-optic phase retardation are analyzed, providing a theoretical basis for the decoupling of linear birefringence and electro-optic phase retardation in OVS. Then, a linear birefringence decoupling method based on linear OVS demodulation is proposed. Its demodulation result is the linear superposition of electro-optic phase retardation and linear birefringence. The electro-optic phase retardation is directly related to the measured electric field, while linear birefringence is introduced by ambient temperature variations. Due to the distinct generation mechanisms of the two, linear birefringence can be separated from the phase retardation and compensated for. On this basis, an OVS linear birefringence compensation method based on AC voltage zero-crossing detection is proposed. Experimental results demonstrate that the linear birefringence of electro-optic crystals in the proposed method is measurable and can be compensated. Within the temperature range of -20℃ to 70℃, the temperature characteristics of linear birefringence in BGO crystals are studied and analyzed. After compensation using the proposed method, the ratio error of OVS is less than 0.257 9% and the phase error is less than 14.254 7′. Finally, an experimental platform for optical power fluctuation and vibration is built to test the optical power independence and vibration stability of the proposed method. The linear demodulation mode based on OVS provides a new perspective for solving the linear birefringence problem in OVS electro-optic crystals.