In order to study the influence of optical devices on the temperature stability of fiber optical current transformer (FOCT), the polarization crosstalk’s influence of 3 types of optical devices： polarizer, LiNbO3 phase modulator and PM(Polarization Maintaining) fiber delay line, on FOCT’s accuracy is analyzed. With each of above optical device’s ambient temperature over a range from -40 ℃ to +70 ℃, the extinction ratio variation of the polarized light from polarizer, the polarization crosstalk variations of LiNbO3 phase modulator and PM fiber delay line, and the error variations of FOCT are tested. The results show that the polarization crosstalk variations with the temperature of the LiNbO3 phase modulator and the PM fiber delay line cause FOCT’s error variation, and LiNbO3 phase modulator is the key component that can affect FOCT’s temperature stability.