Using　guided　wave　dispersion　characteristics,　an　inverse　method　based　on　artificial　neural　network　(ANN)　is　presented　to　determine　the　material　properties　of　functionally　graded　materials　(FGM)　plates.　The　group　velocities　of　several　lowest　modes　at　several　lower　frequencies　are　used　as　the　inputs　of　the　ANN　model;　the　outputs　of　the　ANN　are　the　distribution　function　of　the　volume　fraction　of　the　FGM　plate.　The　Legendre　polynomials　method　is　used　to　calculate　the　dispersion　curves　for　the　FGM　plate.　Levenberg-Marquardt　algorithm　is　used　as　numerical　optimization　to　speed　up　the　training　process　of　the　ANN　model.