Abstract: A class of typical feedback nonlinear systems is analysed. By this analysis, analytical solutions of the steady-state Fokker-Planck equations for first-and second-order systems can be obtained. Based on this algorithm, together with the optimal reduction technique, approximate solutions for Fokker-Planck equation of high order systems can also be obtained. The accuracy of the approximate solutions is compared with that of the traditional RDF method and satisfactory conclusions are obtained.