The　insulation　dielectric　characteristic　of　oil-paper　transformer　is　complex.　In　order　to　study　the　inherent　relationship　between　the　time-domain　polarization　spectrum　characteristic　quantity　of　oil-paper　insulation　and　the　insulation　dielectric　relaxation　response,　the　electrical　characteristic　measurement　method　was　applied　to　the　non-destructive　diagnosis　of　the　transformer　insulation　condition.　The　equivalent　circuit　model　of　transformer　oil-paper　insulation　was　established　and　the　return　voltage　polarization　spectral　characteristic　was　analyzed　in　simulation;　based　on　the　simulation,　the　variation　law　of　the　time-domain　polarization　spectrum　characteristic　quantity　of　oil-paper　insulation　was　investigated　under　different　insulation　conditions.　Results　show　that　the　polarization　spectrum　characteristic　quantity　of　the　time-domain　response　return　voltage　can　be　used　to　effectively　estimate　the　insulation　condition　of　the　oil-paper　insulation　transformer.　The　experiment　results　validate　that　the　equivalent　circuit　model　can　effectively　reflect　the　polarization　process　of　the　insulation　system.　The　change　rule　of　the　return　voltage　characteristic　quantity　with　the　circuit　parameters　is　analyzed　and　obtained　in　simulation,　which　lays　a　theoretical　foundation　for　the　non-destructive　diagnosis　of　transformer　insulation　condition　using　return　voltage　measurement　(RVM)　technique.　©,　2015,　Science　Press.　All　right　reserved.