A novel fiber- optic sensor for the simultaneous measurement of voltage and temperature is presented. The possibility of the separation of the voltage and temperature from a sensing head is analyzed theoritically as follows: a quartz acts as a sensing element, the 1/4 wave plate is put behind the quartz, and the sensing head can simultaneously output two signals. One singnal, involving the Pockels effect, is for voltage measurement; and the another, associated with the optical rotation effect, is for the temperature measurement. The experimental results show that the voltage accuracy of 0.5% can be obtained when the temperature varies by 90 ℃, and the accuracy of the temperature measurement is ±1 ℃.