A finite element model of an eddy current sensor array is built up by electromagnetic-circuit couple method, and the influences of copper foil thickness on sensor's output characteristics are analyzed by the model. It was shown that the amplitudes of sensing coils' output would increase, while the phases would decrease gradually when foil thickness increased. Besides, the discrepancies of phase were diminished when the foil becoming thicker. While the differences of amplitude increased and reached the maximum at thickness of 0.67, then it began to decrease. Generally it is necessary to make the copper foil thickness between 0.17 and 0.33...