The　running　status　evaluation　accuracy　using　insulating　oil　dissolved　gas　analysis　is　not　high　in　the　present　oil-filled　electrical　equipment,　and　the　dispute　of　using　or　not　using　the　C3　gases　as　the　characteristic　gas,　this　paper　used　thermogravimetric　analysis　to　explore　the　insulating　oil　thermal　cracking　characteristics.　particularly,　the　pyrolysis　experiment　was　done　using　the　TGA/SD-TA851　thermogravimetric　analyzer　in　the　condition　of　temperature　range　25　similar　to　550　and　static　air　atmosphere.　The　experimental　material　was　the　domestic　Great　Wall　25th　new　insulation　oil.　In　the　experimental　process,　the　different　heating　rate　(5..　10..　20..　30..　40./min)　was　set　to　explore　the　heating　rate　influence　of　insulating　oil　cracking　characteristics.　By　the　numerical　fitting,　we　calculated　the　thermal　dynamic　parameters　using　differential　method　(Kissinger.　Starink)　and　integral　method　(Coats-Redfern.　FWO)　thermodynamic　theory　and　equation,　The　experiment　and　calculation　results　show　that　(1)　insulation　oil　pyrolysis　process　can　be　divided　into　three　stages,　the　pyrolysis　reaction　order　of　the　main　area　is　1;　(2)　the　thermogravimetric　curve　mild　right　shift　along　with　heating　rate　increasing;　(3)　the　activation　energy　and　frequency　factor　slight　rise　along　with　heating　rate　increase;　(4)　the　difference　of　the　insulating　oil　pyrolysis　properties　is　not　big　for　different　heating　rate;　(5)　the　theoretical　calculation　result　has　a　certain　difference　using　different　thermal　dynamics　equation,　the　Coats-Redfern　equation　calculation　results　most　stable,　the　linear　correlation　coefficient　is　close　to　1.　Above　the　conclusions,　it　provided　a　certain　experimental　basis　for　exploring　the　mechanism　of　the　insulating　oil　heat　aging　cracking　and　the　process　of　C3,　C4　hydrocarbon　gas　composition　producing,　and　using　C3　as　possibility　characteristic　gas.