The invention discloses a method for obtaining a radar scattering area. The method is used for resolving the technical problem that an existing method for obtaining the radar scattering area is low in speed. According to the technical scheme, firstly, a radar scattering model is set up, a firing line is used for simulating an attack direction, association attributes of components are defined, and related data of firing line meshes and the like of the components are obtained; secondly, a projected coordinate system is set up, the data are converted into the projected coordinate system, and RCS calculation is carried out on the related data; at last, real parts and imaginary parts are respectively accumulated to obtain the radar scattering area. Due to the fact that the radar scattering area is obtained by means of a physical optical method and a planar firing line method, the planar meshes are laid on a quadrilateral finite element projected model, 1-N firing lines are produced randomly in units of the planar meshes, and surfaces of the components are scanned through the 1-N firing lines to obtain geometric description data of the radar scattering area. Step sizes of the meshes are regulated according to different precision requirements, radar scattering areas of different precisions are obtained, and the speed for obtaining the radar scattering area is increased.