The　extended　Debye　equivalent　circuit　model　is　commonly　used　to　assist　the　analysis　of　the　oil-paper　insulation　system　degradation　mechanism.　But,　with　the　deterioration　of　the　oil-paper　insulation　medium,　the　internal　polarization　responses　are　various　and　complex,　the　extended　Debye　model　can　not　truly　reflect　the　polarization　responses　of　various　mediums.　So,　this　paper　conducts　further　exploration　based　on　the　extended　Debye　model;　and　firstly　a　parallel-series　equivalent　circuit　model　of　oil-paper　insulation　system　is　proposed,　which　adds　hybrid　branches　to　reflect　the　complex　interface　reaction　and　the　hybrid　branches　combine　with　the　original　RC　series　branches　to　simulate　the　polarization　of　the　medium　itself.　Furthermore,　the　basic　parameter　identification　model　and　recovery　voltage　formula　for　the　parallel-series　circuit　are　studied.　Finally,　simulation　confirms　the　validity　and　superiority　of　the　parallel-series　circuit　with　measurement　data.　At　the　same　time,　compared　with　the　extended　Debye　model,　the　proposed　parallel-series　circuit　can　better　reflect　the　polarization　characteristics　of　oil-paper　insulation　system.　So,　the　parallel-series　equivalent　circuit　of　oil-paper　insulation　system　provides　an　effective　means　in　the　assessment　of　oil-paper　insulation　aging　status.