The traditional way to measure an electric field electrically disturbs the original field, so that can cause a number of measuring problems. Using a Pockels' crystal to measure an electric field has several advantages over electrical methods, such as interference from electromagnetic radiation, high sensitivity and wide frequency bandwidth. This paper presents a kind of new optical method for measuring electric current, this new method makes the Sensing Technology on Pockels effect, Faraday effect and optical Technology together. The sensor combines a Rogowski coil with a passive integrator located in the high-voltage environment. Test results from 20 A to 1.5 kA show the sensor to be highly linear, exceeding 0.2% linearity standards.