The　fundamental　wave　approximation　is　the　main　research　method　of　wireless　power　transfer　(WPT)　technology.　In　this　method,　the　rectifier　load　fundamental　impedance　is　equivalent　to　a　certain　pure　resistance,　which　provides　a　basis　for　system　modeling　and　analysis.　However,　this　method　ignores　the　effect　of　rectifier　load　harmonic　impedance,　which　leads　to　a　large　error　between　the　actual　response　of　system　and　the　theoretical　analysis　result,　affects　the　system　model　accuracy　and　limits　the　further　optimization　design　of　WPT　system.　In　this　paper,　the　WPT　system　based　on　series/series-parallel　(S/SP)　compensation　network　was　taken　as　the　research　object,　the　reason　for　the　error　in　modeling　using　the　fundamental　wave　approximation　was　analyzed　and　an　accurate　calculation　method　based　on　the　iterative　method　for　the　fundamental　wave　and　harmonic　equivalent　impedance　of　the　rectifier　load　was　proposed.　On　this　basis,　an　accurate　circuit　response　model　of　the　WPT　system　was　established,　which　could　effectively　characterize　the　distortion　characteristics　of　the　transmitter　coil　current.　According　to　the　relationship　between　the　system　response　and　the　compensation　network　parameters,　the　optimal　design　method　of　inverter　switching　loss　was　proposed.　Finally,　a　3kW　WPT　system　prototype　was　built.　The　experimental　results　verify　the　correctness　and　feasibility　of　the　theoretical　analysis.　©　2022　Chin.　Soc.　for　Elec.　Eng.