Recovery　voltage　method　(RVM)　is　to　study　insulation　aging　status　of　power　transformer.　Based　on　a　lot　of　test　data　of　recovery　voltage,　the　fuzzy　rough　set　theory　is　proposed　and　used　to　assess　the　oil　paper　insulation　status　of　transformer.　And　the　assessment　system　of　oil　paper　insulation　of　transformer　is　constructed.　Firstly,　the　evaluation　index　of　oil-paper　insulation　status　of　transformer　is　identified　based　on　recovery　voltage　feature　parameters.　Secondly,　the　membership　function　of　fuzzy　partitioning　feature　parameters　for　transformer　test　data　is　obtained　by　using　FCM　clustering　algorithm.　Then,　the　fuzzy　attributes　are　reduced　for　the　assessment　table　of　oil　paper　insulation　statue　in　accordance　with　the　discernibility　matrix,　and　the　assessment　rules　of　oil-paper　insulation　status　are　extracted.　Finally,　the　assessment　system　of　oil-paper　insulation　status　is　built　based　on　the　historical　database.　The　experiments　demonstrate　that　the　assessment　system　is　effective　and　feasible　which　provides　a　new　solution　for　the　assessment　of　transformer　oil-paper　insulation　status.　This　work　is　of　practical　value　in　actual　engineering　applications.　©　2017,　Science　Press.　All　right　reserved.