Abstract: A fiber-optic short-circuit current sensing method is proposed in order to solve the short-circuit test current calibration problem for the AC and DC switch electric appliance. A low-frequency simplified dynamic model of the fiber-optic current sensor was established, and the parameters of the closed-loop signal-detection system were obtained according to the time-domain and frequency-domain characteristics simulation results. The results show that the dynamic performance of the sensor can meet the requirements of tracking the measured short-circuit current. A fiber-optic current sensor calibration device was built, and the calibration results showed that the measurement accuracy of the sensor prototype was better than 0.2% in the range of 5 to 300 kA DC and 5 to 50 kA power frequency. The comparison tests of the AC short-circuit current between the fiber-optic current sensor and the common adopted Rogowski coil were performed. The results showed that for DC short-circuit currents from 6 to 100 kA, the relative error between the shunt and the fiber-optic current sensor was less than 0.3%. For the power frequency short-circuit currents from 10 to 130 kA, the relative error between the Rogowski coil and the fiber-optic current sensor does not exceed 0.2%. The research work provides a new solution for the short-circuit test current measurement.