In　order　to　observe　the　electric-field　distribution　of　insulation　type　test　of　±420　kV　flexible　converter　valve.　This　work　builds　the　3D　model　of　±420　kV　flexible　converter　valve　tower,　Ansoft　is　used　to　simulate　the　electrostatic　field.　Results　show　that:　when　the　flexible　converter　valve　is　doing　a　high　voltage　test,　the　negative　potential　in　suspension　conductors　will　be　generated,　the　potential　distribution　degree　are　various,　this　phenomenon　may　be　caused　by　the　density　difference　of　electric　charges　which　are　induced　by　different　potential　between　left　and　right　valve　components;　Results　of　electric-field　simulation　for　each　component　suggest　that,　electric-field　concentration　likes　to　appear　in　the　corner　of　shield　and　grading　ring,　and　the　tip　position　on　capacitor　metal　component　etc.,　the　corner　of　1th　and　5th　layer　shields　have　the　maximum　electric-field　2　\times10　^{\mathbf{6}}V/m,　this　value　is　\lt　3　kV/mm,　as　for　the　valve　components,　the　electric-field　of　1th　\sim4　th　layers＇　valve　component　are　higher　than　that　of　the　5th　layer＇s　valve　component,　the　reason　may　be　that:　because　the　5th　layer＇s　valve　component　has　a　large　distance　from　the　top　plane(0V),　the　electric-field　lines　distribution　is　sparse,　so　the　electric-field　is　low;　the　electric-field　value　of　insulators　such　as　supporting　insulators　are　105　V/m　order　of　magnitudes,　this　is　lower　compared　to　the　breakdown　threshold　2　\times10　^{\mathbf{7}}　V/m　of　insulator　materials　itself.　©　2018　IEEE.