Power system protection for current measurement and sensor technology have become increasingly demanding. The traditional electromagnetic transformer is unable to meet the requirements. Since the advent of fiber-optic current sensors, researches have focused on how to reduce the influence of birefringence and temperature. Based on the research status of the existing literature on the field of fiber-optic current sensors, new developments, new technologies, nearest discoveries and development prospects, a comprehensive collaction and analysis is given, and the progress of fiber-optic current sensors is shown in detail.