The processes of generation, reception of ultra acoustic wave of EMAT and principle of detecting defect in conductive material were presented in this paper. Then a FEA model of 2D EMAT was set up to detect the internal defects in conductive material based on the electromagnetics theory and finite element method. The accuracy of FEA model was verified by refining mesh elements and result comparison between theoretical calculation and simulation. In the last, simulation result comparisons indicate that the 2D EMAT model can be applied to detect internal defects in aluminum and steel plates, and compared to the steel plate, detecting effect for aluminum plates is more efficient.