Modified　polypropylene　(PP)　is　regarded　as　a　potential　eco-friendly　insulating　material.　Blending　modification,　grafting　modification　and　nanoparticle　doping　have　been　used　to　improve　the　performance　of　PP　with　the　inevitable　introduce　of　impurities.　Copolymerization　is　a　prospective　way　to　reduce　impurity　in　PP,　which　deserves　further　research.　In　this　paper,　isotatic　polypropylene　(iPP),　PP　copolymer　based　on　iPP　(PPC)　and　cross　linked　polyethylene　(XLPE)　were　compared　through　differential　scanning　calorimetry　(DSC),　polarized　optical　microscopy　(POM),　conductivity　and　AC　breakdown　test.　IPP　and　PPC　show　higher　melting　temperature　and　breakdown　field　than　XLPE,　indicating　that　PP　cable　can　withstand　higher　temperatures.　The　results　of　conductivity　show　that　the　current　density　of　PPC　is　smallest　under　same　electric　field　and　the　transition　field　strength　of　PPC　is　highest,　indicating　that　the　deep　trap　level　and　density　of　PPC　may　be　higher　than　those　of　iPP,　which　might　be　caused　by　the　structure　defects　observed　in　the　results　of　POM.　Therefore,　PPC　shows　better　performance　than　iPP　and　XLPE,　suggesting　that　copolymerization　of　PP　is　a　feasible　way　for　future　eco-friendly　cable　insulation.　©　2020　IEEE.