On the basis of the equivalence principle and reciprocity theorem, the multiple scattering up to Nth order by N parallel two-dimensional (2-D) targets arbitrarily located in a Gaussian beam is considered. The first-order solution can be obtained by calculating the scattered field from isolated targets when illuminated by a Gaussian beam. However, it is almost impossible to find an analytical solution for the higher-order scattered field if the 2-D targets are not circular cylinders because of the difficulty in formulating the couple scattered field. In order to overcome this problem, the composite scattering field is studied by employing the technique based on the reciprocity theorem and equivalence principle, and a line integral solution up to Nth order is obtained. In this calculation, only the previous-order scattered field from scatterers and the equivalent surface electric and/or magnetic current density induced by the incident beam are required. Using the approach proposed in this paper, the bistatic and the monostatic scattering fields of a Gaussian beam by parallel inhomogeneous plasma-coated conducting circular cylinders are calculated, and the dependences of attenuation of the scattering width on the thickness of the coated layer, electron number density, collision frequency, and radar frequency are discussed in detail.