By setting up the numerical model of a complicated target, applying outside normal vectors of visible patches of each individual body, and useing Z-buffer algorithm to solve shielding between multi-bodies of complicated targets, the three dimensional scattering problems are analyzed successfully. The currents on the surface of the targets are calculated by solving EM boundary problems. The results obtained by the algorithm are verified by tested results. The method is proved to more accrete, practical, and reliable. The three dimensional scattering distribution could be given in visible way.