This　paper　expands　on　a　theoretical　model　between　the　mechanical　and　electrical　properties　with　acoustic　characteristics　to　obtain　the　theoretical　dispersion　curve　for　Y-cut　LiNbO3　piezoelectric　plate.　The　experimental　dispersion　curve　of　the　LiNbO3　plate　is　extracted　via　V(f,z)　analysis　through　defocusing　measurements　based　on　an　acoustic　microscopy　and　a　lens-less　line　focusing　transducer.　The　objective　function　of　the　inversion　depends　on　the　experimental　dispersion　curve.　The　inversion　method　adopts　a　hybrid　particle-swarm-based　simulated-annealing　(PS-B-SA)　optimization,　which　is　used　for　joint　inversion　of　the　mechanical　and　electrical　parameters　of　LiNbO3.　The　theoretical　dispersion　curve　will　approach　the　experimental　dispersion　curve　by　constantly　modifying　the　mechanical　and　electrical　parameters　in　the　theoretical　model:　the　elastic　constants　(C　(11),　C　(12),　C　(22),　C　(23),　C　(25),　C　(55)),　piezoelectric　constants　(e　(11),　e　(12),　e　(26),　e　(33)),　and　dielectric　constants　(epsilon　(11),　epsilon　(22)).　The　inversed　series　of　constants　are　those　who　make　the　theoretical　dispersion　curve　most　fit　the　experimental　ones.　The　results　show　that　the　inversed　mechanical　and　electrical　parameters　agree　well　with　the　reported　values,　and　the　stability　and　accuracy　of　the　inversion　is　acceptable.　This　research　provides　a　useful　tool　to　characterize　the　mechanical　and　electrical　properties　of　piezoelectric　materials　simultaneously.