Based on the equivalence principle and the reciprocity theorem, the multiple scattering up to Nth-order by N parallel 2-D targets arbitrarily located in a plane wave/Gaussian beam is considered. The first-order solution can easily be obtained by calculating the scattered field from isolated targets. However, due to the difficulty in formulating the couple scattered field, it is almost impossible to find an exact analytical solution for the higher order scattered field. In order to overcome this difficulty, the composite scattering field is studied by employing the technique based on the reciprocity theorem and the equivalence principle and a surface integral solution up to Nth-order is obtained. To evaluate the ith order scattering field，only the i-1th order scattered field from scatterers and the equivalent surface electric and/or magnetic current density induced by the incident wave are required. Using the approach proposed in this paper, the bi- and mono-static scattering width of the incident field by parallel adjacent inhomogeneous plasma-coated conducting cylinders is calculated and the dependence of attenuation of the scattering width on the thickness of the coated layer, the electron number density, the collision frequency and the radar frequency is discussed in detail.