In response to the performance degradation problem of semiconductor light sources and photodetectors in all-fiber optical current sensors during long-term operation with charge, this paper proposes an online measurement technology based on dual redundancy configuration. Firstly, the optical path scheme and working principle of the dual redundant sensor were introduced; Then, by establishing a dual band optical model, the modulation and demodulation measurement scheme of the sensor was explored, and the current demodulation error and temperature influence error of the sensor were simulated and analyzed; Finally, a sensor prototype was built, and nonlinear and temperature error tests were conducted on the sensor prototype. A real-time monitoring method was proposed to verify the accuracy of the sensor, and the effects of magnetic field interference and vibration interference were studied. The results show that within 5%Ir~ 120%Ir(Ir=500A), the prototype measurement error is less than ±1%; Within the range of -40℃ to +80℃, the measurement error is less than ±0.1%, and accurate self-monitoring with the measurement error of less than ±0.2% is achieved; Under the influence of magnetic field interference and vibration interference, the measurement error is also less than ±0.2%. The developed dual redundant all-fiber optical current sensor has achieved practical measurement accuracy requirements.