At　present,　high-voltage　direct　current　(HVDC)　transmission　technology　is　more　and　more　widely　used　in　long-distance　transmission　because　of　its　low　line　cost,　low　loss　and　easy　control.　But　under　high-voltage　DC　electric　field,　the　accumulation　of　space　charge　will　occur　in　the　DC　insulation　structure,　leading　to　the　distortion　of　electric　field,　and　thus　influencing　the　aging　and　failure　of　the　insulation.　Due　to　the　limitation　of　space　charge　measurement　methods,　we　can　only　obtain　the　space　charge　distribution　of　simple　structures　(e.g.　films　or　coaxial　cable　samples),　and　the　distribution　of　space　charge　in　complex　insulation　structure　cannot　be　directly　measured.　Therefore,　it　is　necessary　to　simulate　the　distribution　of　space　charge　in　complex　insulation　structure　using　simulation　software　based　on　the　existing　space　charge　transport　theory.　In　this　paper,　based　on　COMSOL　Multiphysics　software,　the　space　charge　and　field　distribution　in　a　3-dimensional　structure　can　be　calculated.　The　model　used　in　this　paper　is　the　bipolar　charge　transport　model,　to　simulate　the　distribution　of　space　charge　and　electric　field　in　various　insulation　structures　under　the　action　of　high　voltage　DC　electric　field.　This　paper　calculates　the　space　charge　and　electric　field　distribution　in　a　cable　joint　under　temperature　gradient.　Comparing　with　traditional　way　which　only　the　conductivity　was　taken　into　consideration,　this　method　can　accurately　reflect　the　electric　field　distortion　caused　by　the　difference　of　carrier　injection,　extraction　and　migration.　©　2020,　Springer　Nature　Switzerland　AG.