Abstract: In the electricity system,the unit of magnetism-photo optical fiber can be made with the Faraday Effect of the magnetic-field of the power line.The unit could be put at the spots which need to be real time measurement and control,and by means of the wave division multipiexing(WDM)technology of optical fiber net,the real time data of all spots can be tran smited to the central computer.In this way,the system of distributed optical fiber electricity current supervision and control can be constituted.