A novel iterative algorithm based on the measured equation of invariance （IA-MEI） is proposed for the scattering analysis of multi-cylinders with arbitrarily shaped cross-sections. By using the MEI’s

the truncated mesh boundary

can be much close to the surface of each cylinder

which resuhs in dramatical savings in memory needs and computing time. Based on the invariance to excitation of MEI

the MEI coefficients at truncated boundary nodes of the meshes around each cylinder may be used repeatedly in the iterative procedure

which also greatly reduce the computing time. The results of some circular cylinders are in good agreement with exact solutions. Besides

the scattering fields of some electrically large compound multi-cylinder structures are presented.