For　propagation　of　Lamb　waves　in　a　transversely　isotropic　functionally　graded　material　(FGM)　plate　with　material　parameters　varying　continuously　along　thickness　direction,　power　series　technique　is　adopted　for　theoretical　derivations　and　the　phase　velocity　equations　are　obtained.　Numerical　calculations　are　performed　to　study　the　influence　of　material　parameters　graded　variation　on　dispersion　relations.　These　relations　are　compared　with　those　in　corresponding　ceramic　and　metal　plates,　respectively.　Further　investigation　is　carried　out　to　consider　influence　of　material　parameters　graded　variation　on　wave　structures,　behavior　of　Lamb　waves　in　such　typical　inhomogeneous　medium.　Results　obtained　may　provide　theoretical　basis　for　the　ultrasonic　characterization　and　testing　of　functionally　graded　materials　and　structures.