Electrical　tree　is　one　of　the　main　reasons　for　cable　failure.　In　this　paper,　the　space　charge　evolution　and　electrical　tree　characteristics　under　polarity　reversal　voltage　with　varied　temperature　in　silicone　rubber　(SIR)　are　carried　out.　Results　show　that　as　temperature　rises　from　30　degrees　C　to　120　degrees　C,　electrical　tree　initiation　voltage　declines　by　17.8%.　Meanwhile,　the　trees　become　denser,　and　the　tree　length　is　larger　correspondingly.　In　order　to　ascertain　the　charge　transportation　and　its　influence　on　tree　initiation　process　under　polarity　reversal　voltage,　we　build　a　bipolar　carrier　transportation　model　with　needle-plate　electrode.　Space　charge　transportation　characteristics　and　corresponding　electric　field　are　simulated.　Moreover,　the　evolution　model　of　electrical　tree　under　polarity　reversal　voltage　is　discussed.　The　presence　of　homo　space　charge　leads　electric　field　to　become　larger　during　the　voltage　reversal　process.　The　segment　relaxation　of　SIR　and　more,　deeper　space　charge　injection　make　tree　initiate　more　easily　at　higher　temperature.