The　return　voltage　polarization　spectrum　is　analyzed　based　on　the　results　of　field　test　by　RVM5461　tester,　the　parameters　of　transformer　relaxation　mechanism　are　analyzed　based　on　the　extended　Debye　model,　the　characteristic　variables　of　depolarization　current　energy　spectrum,　which　reflect　the　aging　condition　of　transformer　oil-paper　insulation,　are　analyzed,　and　a　standard　state　parameter　table　is　established　based　on　the　measured　data　of　multiple　transformers.　A　comprehensive　weighting　method　combining　subjective　weighting　and　objective　weighting　is　adopted　to　determine　the　weights　of　different　time-domain　characteristic　parameters　and　a　comprehensive　evaluation　system　combining　multi-index　evaluation　method　and　evidence　theory　is　established　for　assessing　the　insulation　state　of　transformer　oil-paper.　The　results　of　case　test　show　the　effectiveness　of　the　proposed　method.　©　2017,　Electric　Power　Automation　Equipment　Press.　All　right　reserved.