Abstract: A scattering parameter circumferential distribution chart was employed to present the 2D scattering characteristics of defects. The FE model of a Lamb wave interaction with defects was investigated. A dual-element exciting method was used to produce a pure S0 mode as incident wave. An absorbing boundary was used to eliminate the wave reflection of a border. Scattering signals in all the directions were acquired and post-processed so that a scattering parameter circumferential distribution chart could be plotted. This FE model was validated experimentally and a good agreement was obtained between FE and experimental results. The interaction of an S0 mode with a trough-thickness hole and a crack was studied and scattering parameter distribution charts with 0 degree incident were measured. The charts could be used to characterizing the kinds of defects. The energy distribution of multi scattering modes also was studied. The results show that the single mode exciting and multi-modes receiving could avoid undetected defects.