In this manuscript, a novel approach for an approximate solving of coupled Schrodinger-Poisson (SP) equations in the accumulation layer of semiconductor is described. This approach, based on the homotopy perturbation method (HPM), gives an approximate analytic solution of SP system which at the same time has a relative simple mathematical form, as well as a high degree of accuracy. A good agreement between HPM solution and exact solution of SP system indicates on the utility and sufficiency of the HP method