The nonlinear correction system of the fiber Bragg grating (FBG) current transfo rmer based on field-p rogrammable gate array (FPGA) is studied in order to improve the measurement pre cision of the curren t transformer and reduce the phase error.This paper analyzes the hy steresis characteristics of the giant magnetostrictive material (GMM).Vari able parameter curve fitting method is adopted to realize the nonlinear correct ion of data processing.In order to rachieve the real-time nonlinear corre ction o f the current transformer output and reduce the hysteresis characteristics influ ence of GMM m aterials on FBG current transformer,data collecting,filtering,cachi ng,frequency division,correction processing and data conversion are all comp leted by FPGA.By use of the correction unit,the phase error of current transfo rmer is reduced from 7° to 1°,the amplitude error is less than 1%,so the measuring accuracy of the current test system is improved.