In order to eliminate the sensitivity between common eddy current sensor toward the pending-tested materials, this paper measured the resistance and inductive reactance of the Φ5 probe coil through experiments, which covers six types of materials include copper, aluminum, A3 steel, 45# steel, 1Cr18Ni9Ti and DT4 iron. According to fitting processing experimental data, this paper proposed and demonstrated a projection-changing approach which can erase the material sensitivity. Moreover, this paper introduced a structural and general thought which can make use of circuit to realize the scheme with introducing the functions of main components in this circuit. The calculation error of this method is less than 5%.