Abstract: The composite electromagnetic scattering characteristics of a coated target above a dielectric rough surface are studied by finite element boundary integral (FE-BI) method in this paper. The FE-BI formulation for the electromagnetic scattering from a two-dimensional coated target above a one-dimensional dielectric rough surface is derived. In the simulation, the fields inside the coated target are modelled by powerful finite element method and the multi-interactions between the coated target and the rough surface are taken into account by boundary integral equation method. Combined with the Monte-Carlo method, the scattering from a coated cylinder above a dielectric Gaussian rough surface is numerically calculated and the influence of the relative permittivities of the coating, the roughness of the rough surface and the relative permittivities of the rough surface on the bistatic scattering coefficient of the composite model are analyzed. The numerical results show that, compared with the traditional MoM, the efficiency of our method is slightly lower in dealing with the ideal conductor model. But our method can deal with the complex medium electromagnetic scattering problem which MoM is difficult to deal with, and the calculation accuracy is higher.