The invention discloses a medium rough surface electromagnetic scattering simulation method based on a multi-zone model moment method. The method includes the steps of inputting a medium rough surface power spectral density function and rough surface parameters, obtaining position coordinates of N scattering surface elements on a rough surface through a Monte Carlo method, dividing the rough surface into a main zone and a non-main zone, obtaining equivalent current on the surface elements of the two zones respectively, obtaining an electromagnetic scattering coefficient of the rough surface, and achieving medium rough surface electromagnetic scattering simulation. According to the method, zone division is performed on the rough surface, a boundary integral equation is built through the moment method in the main zone which has large influences on scattering results, the equivalent current of the main zone is obtained, the equivalent current is obtained approximately in the non-main zone, the number of unknown quantities is lowered under the premise that certain accuracy is guaranteed, internal storage is reduced, calculation efficiency is improved, the technical problem of actual large-zone medium rough surface electromagnetic scattering simulation is solved, and the method is applied to rough surface radar scattering property study in the fields of national defense and civil use.