Abstract: Abstract In this paper, an inverse algorithm of two-way parabolic equation (2WPE) method is presented and investigated on the basis of the inverse algorithm of one-way parabolic equation (1WPE) method, i.e. inverse diffraction parabolic equation method. At a certain receiving point, the backward-fields reflected by obstacles are obtained and inversely propagated, and then the location and height of the obstacles can be determined by the inverse diffraction fields. Simulation results of the inverse algorithm of 2WPE method for the scenario of single knife-edge is provided. For single knife-edge, the effects of the antenna height and the knife-edge location on the positioning accuracy is analyzed, and the accuracy is very high.