Abstract: Based on the Born approximation, an analytical theory for computing the electromagnetic field in weak fluctuating multilayered media with source is developed. In the theory, the source can be placed in an arbitrary layer among N-layers of the media. On the assumption that every layer among N-layers of the background media is isotropic and varies sufficiently slowly along the vertical position, the average and scattering fields represented by their reflection cofficients, transmission coefficients, impedances and wave number ratios are obtained by W. K. B method and the dyadic Green's function of electric and magnetic typed.