Abstract: The attenuation of the electromagnetic wave in the non-uniform plasma slab cling to a metal plane is studying in this paper. The plasma slab is divided into a number of sub-slabs each of which is dealt with as a uniform slab. Detailed numerical calculations are conducted on Epstein-distributions. The effects of electron number density, momentum transfer collision rate, magnetic field and angle of incidence on the attenuation are taken into account, and get the character of plasma's absorbing electromagnetic wave.