高压变电站中用于电力系统电流测量的全光纤电流传感器由于具有传统电流互感器无法比拟的优点，具有广阔的应用前景。Sagnac 环形电流互感器是在干涉式光纤陀螺结构上发展起来的一种互感器结构。由于基于Sagnac 干涉仪技术的光纤陀螺的实用化，用此技术来实现 Sagnac 环形电流互感器的实用化成为电流互感器的热点。本文首先介绍了Sagnac 环形电流互感器的基本原理和结构，通过建立电流互感器的光学矩阵模型推出了电流互感器的基本公式，然后综述了其发展过程，研究成果以及存在的主要问题，重点讨论了温度漂移和温度稳定性。

All-fiber Optic Current Sensors (AFOCS) which are used to measure the power supply system in high-voltage substations have incomparable advantages to conventional current transformers, so more and more attention is paid on it. The structure of Sagnac Ringlike Optic Current Sensors (SROCS) is developed on the structure of interferometric fiber-optic gyroscope. Because of the realization of gyroscope based on the technology of Sagnac interferometers, the same way to realize SROCS becomes one of the hotspots of current transformers. The basic principle and structure of SROCS are analyzed and researched firstly. The formulation of optic current sensor is launched by the establishment of optical matrix model, and then the development condition, research results and main problems are described with emphasis on the vibration stability.