Abstract: A novel sensor with detection and signal processing circuit of micro-magnetic physical fields is proposed. The approach is based on the physical characteristics of Fe-Co-Si-B amorphous wires, and the theory of giant magneto-impedance effect and resonant circuit. With improvement in forms and algorithms of magnetic sensor, the circuit ensured the characteristics of high sensitivity, high detection precision, fast response and small power consumption. Experiments showed that the measurement range was 0~1T and resolution 100nT. Using the micro-magnetic sensor, the static magnetic field around a tank was analyzed, which improved the accuracy of the model.