Based　on　Debye　equivalent　circuit　model　and　time-domain　dielectric　response　principle,　a　return　voltage　function　model　of　insulation　dielectric　is　proposed　to　reflect　its　response　process,　which　is　used　to　identify　the　topological　structure　of　oil-paper　insulation　system.　The　feasibility　and　correctness　of　the　proposed　model　and　identification　method　are　verified　by　the　experimental　results　and　the　aging　condition　of　transformer　oil-paper　can　be　preliminarily　diagnosed　by　the　number　of　equivalent　polarization　branches.　©　2016,　Electric　Power　Automation　Equipment　Press.　All　right　reserved.