To　solve　the　problem　of　fuzzy　and　uncertainty　in　evaluation　of　transformer　oil-paper　insulation　condition,　we　proposed　a　method　for　evaluating　the　state　level　of　oil-paper　insulation　based　on　a　non-standard　model.　Firstly,　the　traditional　method　of　approaching　degree　was　abandoned,　and　the　weight　allocation　coefficient　wk　was　introduced　to　change　the　problem　of　weight　distribution　on　each　index　into　the　optimization　of　objective　function　based　on　the　sum　of　squares.　Secondly,　the　grey　target　classification　method　based　on　sample　set　was　adopted,　and　a　circular　grey　target　classification　table　for　state　classification　of　oil-paper　insulation　system　was　analyzed.　Finally,　a　specific　example　was　given　to　validate　feasibility　of　this　method.　The　results　show　that　the　evaluation　results　of　the　proposed　algorithm　and　the　actual　operation　state　of　transformers　have　consistency.　This　study　can　provide　a　useful　reference　for　rational　allocation　of　weight　coefficients　and　calculation　of　grade　intervals　in　condition　assessment　on　oil-paper　insulation.　©　2018,　High　Voltage　Engineering　Editorial　Department　of　CEPRI.　All　right　reserved.