A non-contact current sensing system composed of tunneling magnetoresistance (TMR) sensor array without magnetic core structure is proposed. It provides a solution for the current measurement of concealed wires in the wall, which is suitable for leakage current detection and fault location. The characteristics of the magnetic field generated by the electrified wire are analyzed, the mathematical model of the electrified wire and the sensor array at different relative positions is studied, and the value method of the coaxial sensor spacing under different working conditions is proposed. At the same time, the main sources of signal interference and the main causes of signal error of the non-soft magnetic shielding device are analyzed, and the mathematical model of signal detection is proposed, and the error correction methods are proposed for different types of errors. Finally, experiments are carried out under different working conditions, and the results show that the developed non-contact current detection device has good accuracy and linearity, which verifies the practicability of the current measuring device and the feasibility of the measurement method.