Optic polarization states of sensing light wave in Sagnac fiber optic current transformer are limited. However, several factors induce optic polarization error, and non-ideal polarized light waves cause the interference signal crosstalk in transformer, including polarizer, quarter-wave retarder, splice angular, and so on. Focused on optical polarization error in fiber optic current transformer, we build optical polarization error models by using Jones matrix, then, analyze the evolution process of linear optic polarization state and circular optic polarization state in Sagnac fiber optic current transformer. Based on models of polarization state in Sagnac fiber optic current transformer, we investigate the influence of several main error factors on optical polarization error characteristics and performance theoretically, including extinction ratio in polarizer, splice angular between quarter-wave retarder and polarization maintaining fiber, phase delay in quarter-wave retarder.