The fiber quarter-wave plates are an important part of fiber-optic current transformers (FOCT). In order to decrease the error caused by the quarter-wave plates on the ratio under the varying temperature environments, more accurate relationship between the temperature and the phase delay of fiber quarter-wave plates is required. Based on the intensity method, a measuring way of the temperature dependence of the phase delay of quarter-wave plates is put forward. It is applied to measure fiber quarter-wave plates in real time and continuously. A mathematical model of the test systems is established by using Jones matrix, and the temperature characteristics of the quarter-wave retarder are tested. The experimental results show that: the relationship between the temperature and the phase delay is linear, and the temperature coefficient of inland quarter-wave plates is much larger than that of the abroad ones; in the temperature self compensation technology of ratio error of FOCT, the smaller the temperature coefficient of the phase delay of quarter-wave plates is, the higher the self compensation limit precision is and the wider the original phase retardation is.