Abstract: On the basis of Stratton-Chu equation, the method gives simple physical optics equation that calculate the RCS of theconvex coated metal surface, and considering wedges scattering field, electromagnetic scattering characteristic of wedge withdielectric coating and conducting wedge are different, the wedge with dielectric coating scattering field is resolved by using EdgeEquivalent Currnet(EEC), the radar cross-section (RCS) of typical target such as metal plate coated with RAM, combinedcone-cylinder coated with RAM and a missile coated with RAM are calculated, the calculated results are consistent with the resultfrom measurement and MOM, which verity effectivity and accuracy of the method. This method is specially effective to computeRCS of large electric size targets.