Wireless　power　transfer　is　widely　used　due　to　its　safety　and　convenience.　The　rectification　circuit　is　an　important　part　of　the　WPT　system.　Different　rectification　circuits　and　input　parameters　may　lead　to　different　responses　and　output　gains　in　the　actual　applications.　Usually,　the　fundamental　harmonic　analysis　method　is　adopted　to　analyze　the　WPT　system＇s　performance.　However,　this　method　cannot　present　the　differences　between　different　parameter　applications.　It　is　because　only　the　fundamental　harmonic　is　taken　into　consideration.　In　this　paper,　the　influence　of　harmonics　is　studied.　Moreover,　the　equivalent　impedance　model　of　the　rectification　circuits　is　built.　It　can　take　the　input　and　rectification　circuit　parameters　into　consideration,　which　is　quite　different　from　the　traditional　method.　Based　on　the　equivalent　impedance　model　of　the　rectification　circuits,　the　response　model　of　the　WPT　system　can　be　analyzed.　Finally,　a　WPT　system　is　used　for　the　validation.　The　key　waveforms　calculation　results　are　almost　the　same　as　the　measured　results.　It　verifies　the　proposed　method　to　be　correct　and　useful.　It　provides　a　good　basis　for　WPT　system　optimization.　©　2023,　The　Author(s),　under　exclusive　license　to　Springer　Nature　Singapore　Pte　Ltd.