The problem of directed waveguide mode scattering in the irregular planar optical waveguide (PWG) is solved with the help of the theory of perturbations. The solution of the inverse waveguide scattering problem consists in restoring of autocovariance function and determination of irregularities' parameters by the measuring data of scattering diagram in the far zone. The computer simulation allow approving, that our method permits to receive approximate correct solution of the inverse problem with rms error of restoring of the given autocovariance functions no more than 35% in the presence of high real noise (SNR ≥ 1). The statistic parameters of irregularities in this case can be determined with an error less than 15-30 %.