Abstract: The technology of the optical measurement of current is reviewed.Several different approaches being developed and their principles are described.The major problems of these approaches and their probable solving methods are discussed.At the present stage,bulk glass transducer technology is more mature than others and some commercial products have been developed.The hybrid transducer has a higher accuracy but the active circuit in its sensing head involves a complicated power supply problem which has not been solved completely.The all-fiber typeis the developing goal of optical current transducer and its main problem at present is the linear birefringence in sensing fiber.This problem is dependent on the further development of new fiber material and integrated optical devices.Finally,the developing trend and the commercial prospects of optical current transducers are analyzed.