The main temperature error sources of all-fiber optical current transformer（FOCT） are analyzed. The errors caused by fiber λ/4 waveplate and Verdet constant are calculated in theory. A temperature error compensation technology is presented， which uses the error caused by λ/4 waveplate to compensate for the error caused by Verdet constant by choosing appropriate original phase retardation angle of the λ/4 waveplate. The experimental results show that FOCT can satisfy the temperature cycle accuracy requirements of the 0.2 s class measuring electronic transformer.