Human　body　communication　(HBC)　has　the　advantages　of　low　power　consumption,　low　radiation　and　anti-interference　ability,　which　has　broad　application　prospects　in　entertainment　and　health　care.　Accurate　human　channel　characteristics　will　contribute　to　the　development　of　HBC.　This　paper　explores　the　effect　of　channel　length　and　electrode　size　on　human　body　channel　phase　characteristic.　A　galvanic　coupling　human　body　communication　experimental　platform　was　built.　The　measurement　results　show　that　in　the　low　frequency　band,　the　phase　transition　is　less　than　the　high　frequency.　When　the　frequency　is　in　the　range　of　200 kHz　to　300 kHz,　the　phase　will　oscillate.　Increasing　the　electrode　size　can　improve　phase　oscillation.　This　paper　provides　a　reference　for　the　application　of　human　body　communication　in　long　channel　and　the　miniaturization　design　of　transceiver.　©　2020,　Springer　Nature　Switzerland　AG.