Overvoltage　caused　by　faults　or　switching　is　one　of　the　decisive　factors　affecting　the　insulation　level　of　equipment　in　UHVDC　transmission　systems.　As　for　±1　100　kV　transmission　projects,　there　has　been　no　clear　conclusion　about　the　overvoltage　distribution　characteristics　along　transmission　lines.　This　paper　studies　characteristics　of　the　overvoltage　distribution　along　±1　100　kV　transmission　lines　after　building　the　simulation　platform　of　±1　100　kV　UHVDC　transmission　systems　with　the　use　of　PSCAD　software.　The　typical　fault　conditions　are　simulated　such　as　monopolar　line-to-ground　fault　and　line-broken-down　fault　of　transmission　lines.　The　distribution　characteristics　of　overvoltage　along　the　line　under　different　faults　are　obtained.　The　simulation　results　show　that　the　arresters　installed　along　the　lines　can　significantly　reduce　the　switching　voltage　level　of　DC　lines.　The　voltage-current　characteristics　and　the　installation　density　of　the　arresters　along　the　line　have　an　important　influence　on　the　overvoltage　suppression　effect.　Through　the　comparative　analysis,　a　configuration　scheme　of　arresters　along　the　lines　is　proposed,　which　has　a　great　effect　for　overvoltage　suppression.　The　results　are　instructive　for　the　design　of　insulation　coordination　in　practical　projects.　©　2019　Institution　of　Engineering　and　Technology.All　right　reserved.