Abstract: The resean loop mothed for solving the scattering field of complex targets in resonance region is presented.The idea of wire grid is using the induction current flowing on the three dimensional wire grids to simulate the continuous conduct surface excited by the incident electromagnetic wave.Unlike the single wire grid model published before,we use the resean loop model to simulate every continuous conduct facet,so the Kirhoff Law is automatically satisfied on each junction.Based on analyzing the geometric model of the targets,the RCS of complex aircrafts are obtained by using corresponding EM model and CGFFT in resonance region.Numerical results verify the correctness and usability of the resean loop electromagnetic model presented by this paper.