The　HVDC　converter　valve　is　an　important　equipment　to　realize　power　transmission　under　high-voltage　direct-current　condition.　The　reliability　of　high-voltage　direct　current　(HVDC)　converter　valve　directly　affects　the　operation　of　HVDC　converter　valve.　At　first,　the　typical　situations　inside　the　converter　valve　over-voltage　are　analyzed　and　summarized　in　this　article,　and　then　analyzes　the　broadband　model　of　each　component　in　the　converter　valve,　and　establishes　the　broadband　model　of　the　valve　tower　based　on　this.　Then　this　paper　analyzes　the　over-voltage　distribution　of　the　converter　valve　under　several　fault　conditions　through　model　simulation,　such　as　HEMP,　operating　over-voltage　and　lighting　over-voltage.　Through　the　summary　of　several　over-voltage　distributions,　the　over-voltage　mechanism　of　HVDC　converter　valve　is　more　deeply　understood　and　the　theoretical　guidance　for　improving　the　reliability　of　the　HVDC　converter　valve　during　high-voltage　power　transmission　is　provided.　©　2021　IEEE.