The ideal discontinuities existing on the surface of weapons and equipment have important effect on the objects’ electromagnetic scattering characteristics. According to the theory of electric field superposition, and based on the actual discontinuities and carrier, a novel computational approach for the electromagnetic scattering extraction of ideal discontinuities is proposed. And combining this novel approach with darkroom test and MLFMA(Multilevel Fast Multipole Algorithm), the electromagnetic scattering characteristics of ideal single-column, multi-column gap and step discontinuities are studied, and the correctness and efficiency of the new extraction approach are verified. The novel computational results show that this approach is not only simple and efficient, but also possesses consistent computation accuracy with MLFMA, which could fast extract the electromagnetic scattering characteristics of ideal single and multiple columns discontinuities. Besides, the ideal discontinuities have significant effects outside the specular scattering region, especially for the effects of step discontinuities, and ideal multi-column scattering also has strong coupling, performed as more scattering peaks, which are the effects of superposition of each ideal column electromagnetic discontinuities.