Relation　between　line　shape　factor　and　insulting　oil-paper　from　perspective　of　microscopic　dynamics　is　analyzed,　because　aging　of　transformer　insulating　oil-paper　cannot　be　evaluated　directly　with　conventional　time-domain　dielectric　response　method.　Different　dielectric　polarization　processes　hidden　in　polarization　current　were　resolved　individually　with　the　proposed　time-domain　differential　method.　The　method　not　only　solved　line　shape　factor,　but　also　determined　polarization　branch　number　directly.　Analysis　results　of　transformer　test　curves　show　that　polarization　branch　number　changes　with　insulation　conditions.　When　transformer　insulation　condition　changes　from　good　to　seriously　deteriorated,　polarization　branches　number　increases;　when　insulation　condition　is　improved,　polarization　branches　number　decreases.　Corresponding　line　shape　factors　increase　when　oil-paper　insulation　dielectrics　deteriorate　individually;　on　the　other　hand,　they　decrease　as　insulation　conditions　improve　individually.　©　2017,　Power　System　Technology　Press.　All　right　reserved.