Abstract: A novel optical current sensor detecting high alternating current is designed based on Grating Light Valve technology.This device features excellent frequency response,temperature stability and sensitivity at high current,while its fabrication is simple and cost-effective.Finite element analysis and numerical calculation reveal that the alternating current with peak value ranging from 500A to 2000A can be detected by the device;1st order resonant frequency is approximately 60kHz and the sensitivity at high current can reach 0.19dB/A;when temperature varies ±50K,measurement error is around 0.7%.