A new magneto-optic current sensor with a dual-orthogonal configuration is proposed and demonstrated, which can resolve the problem which value of high-current pulses is ambiguous from the Faraday rotation in the conventional magneto-optic current sensor. In this dual-orthogonal configuration, the transmission axis of the polarizer makes two given angles, which are 0 degrees and 45 degrees , with the orientation of the s-polarized lights of two polarizing cube beam splitters. If the intrinsic linear birefringence of the sensing element is one-fourth less than the Faraday rotation generated from the high-current pulse, the measurement current influenced by it can be ignored and four outputs of the magneto-optic current sensor are in quadrature. The value of the current pulse can be calculated by an arctangent data reduction method, which can avoid the insensitive zone of the sine function, where the measurement current has a reduced accuracy. A measurement of the high-current pulse (up to 720 kA) of an electric gun, with good theoretical accuracy ( approximately 3%) and in agreement well with that of the calibrated Rogowski coil, is launched.