In　this　paper,　conductance　characteristics　of　the　two　kinds　of　XLPE　materials　such　as　XLPE　and　XLPE/SiO2　nano-composite　were　measured　under　high　stresses　(2-70kV/mm)　and　under　different　temperatures　(e.g.　20　degrees　C,　50　degrees　C　and　80　degrees　C),　after　both　XLPE　were　treated　through　different　thermal　treatment　methods　including　thermal　treatment　and　thermal　poling　treatment.　The　test　results　show　that　nanodoped　XLPE　can　increase　charge　injection　threshold　and　decrease　current　density　effectively,　and　pre-stressing　is　facilitate　to　improve　charge　injection　threshold　and　reduce　current　density.　Besides,　the　slopes　of　both　XLPE　curves　in　lgJ-lgE　double　logarithmic　coordinates　decrease　with　the　increase　of　temperature　under　high　fields,　indicating　the　dependence　of　activation　energy　of　XLPE　materials　on　electrical　stress.