The accident rate of the lightning arrester is increasing year by year, which is to reduce the accident and maintain the stable operation of the system. Based on the principle of optical fiber current sensor, a fault detection method of zinc oxide arrester is proposed,the resistance leakage current of zinc oxide arrester valve is measured by optical fiber current sensor, and the change of resistance leakage current is analyzed, the validity and accuracy of this method under various faults are verified by experiments.The results show that this method can clearly see the change of leakage current and detect the fault of zinc oxide arrester.This study provides a reference for the development of surge arrester fault detection methods in China.