An electromagnetic scattering model for a layer of randomly distributed vertical long cylinders over a dielectric half space is developed in this paper, which takes into account multiple scattering terms up to second order. Closed-form expressions for the second-order scattering fields are derived for two adjacent cylinders in the near field of each other based on the reciprocity theorem and are validated by comparison with numerical results based on the moment method. By applying the Monte-Carlo simulation technique, the backscattering properties of a layer of conducting cylinders above a conducting ground plane and a layer of dielectric cylinders above a dielectric ground plane are studied. The simulation results show that the HH polarization solution is dominated by single scattering for the layer of cylinders whose diameters are fairly small and lengths are much long compared with the excitation wavelength. The secondary scattering shows great effect on the VV polarization results in the vicinity of the Brewster angle of dielectric cylinders. The simulation results are compared with those obtained by the radiative transfer (RT) method which is based on the addition of intensities and the comparison shows that the RT solutions could not give correct results for the medium composed of vertical long cylinders.