In　order　to　explore　how　the　electric-field　distributes　in　the　surface　layer　of　metal　component　when　the　hybrid　circuit　breaker　is　turning　off,　we　established　a　3D　model　of　±535　kV　HVDC　hybrid　circuit　breaker,　and　employed　the　Ansoft　electrostatic　field　analysis　software　to　simulate　and　calculate　the　electric-field　in　valve　tower　structure　of　circuit　breaker.　Simulation　results　show　that,　when　the　short-circuit　current　generates,　the　circuit　breaker　turns　off　immediately,　at　this　time,　the　maximum　electric-field　occurs　at　the　chamfer　of　shield　of　valve　tower,　which　is　1.8×106　V/m,　lower　than　the　corona　electric-field　of　air　of　3×106　V/m.　As　for　the　valve　components　installed　in　different　valve　layers,　the　surface　electric-field　shows　a　decreasing　trend　firstly　and　then　shows　an　increasing　trend　with　the　layers＇　increasing;　the　middle　layer　part　of　MOV　arrester　components　has　a　higher　electric-field,　which　is　about　2×105~5×105　V/m.　When　the　circuit　breaker　turns　off,　the　surface　electric-field　of　metal　component　is　lower　than　2×106　V/m,　which　meets　the　requirements　of　insulation　design.　The　experiment　proves　that　the　circuit　breaker　can　turn　off　the　short-circuit　current　normally,　and　the　components　installed　in　the　circuit　breaker　all　keep　a　good　insulation　property.　©　2019,　High　Voltage　Engineering　Editorial　Department　of　CEPRI.　All　right　reserved.