The　internal　state　information　of　lithium-ion　batteries,　such　as　lithium-plating,　state　of　charge,　etc.,　which　can　be　reflected　by　the　internal　structure　of　the　battery　and　its　mechanical　properties.　During　the　battery　charging　process,　the　Young＇s　modulus,　density　and　porosity　of　the　internal　electrode　materials　will　change.　Ultrasonic　non-destructive　testing　can　be　used　to　characterize　the　internal　state　of　the　battery　and　obtain　the　relationship　between　wave　propagation　information　and　internal　state.　This　study　describes　in　detail　the　reflection/transmission　characteristics　of　ultrasound　in　lithium-ion　batteries.　Based　on　the　working　principle　of　lithium-ion　battery,　the　porosity　in　the　electrode　of　the　lithium-ion　battery　is　considered　by　Biot　theory,　and　the　reflection/transmission　coefficient　of　the　single　cell　is　solved　by　the　the　transfer　matrix　method.　As　the　thickness　of　the　lithium　plating　layer　increases,　the　angle　spectrum　and　the　frequency　spectrum　show　regular　movement,　which　makes　it　possible　to　further　characterize　the　thickness　of　the　lithium　plating　layer.　The　results　obtained　by　the　finite　element　simulation　are　highly　consistent　with　the　theoretical　calculation　method,　which　further　verifies　the　feasibility　of　the　method.