The micro-current sensor is the key equipment for picking up the weak current signal.However，in practical applications such factors as temperature，humidity，strong electromagnetic interference，surge current，and run-time drift will change its phase characteristics，exerting a significant impact on phase-sensitive measurement，as in the case of the dielectric loss tan δ measurement for electrical equipment insulation online monitoring.To solve this problem，the FastICA algorithm is introduced in this paper.The field programmable gate array（FPGA）implementation of the phase self-calibration system for the micro-current sensor is proposed.The floating-point units are used in this implementation and the structure of the algorithm is optimized.The results show that the measuring precision，speed，and the fault-tolerant ability of the designed system meet engineering requirements.