Finite element tearing and interconnecting method(FETI) is used in analyzing electromagnetic scattering of complex medium.It decomposes computational space and complex medium.With reasonable operations of algebra,a 3D problem is changed to a 2D problem.It reduces computational complexity.By using Krylov solver,computation of reverse matrix is avoid in the equation about interface system.Numerical results show that the method is accurate and efficient for electromagnetic scattering of complex medium.