For　long　distance　and　large　capacity　transmission　problems,　high-voltage　direct　current　(HVDC)　transmission　is　a　suggestive　alternative.　In　the　design　and　construction　process　of　HVDC　transmission　project,　analysis　on　overvoltage　and　resonance　characteristic　of　key　equipment　is　indispensable.　This　paper　employs　a　method　to　construct　a　passive　broadband　model　for　the　converter　valve.　The　Vector　Fitting　(VF)　method　is　adopted　to　get　a　fitting　curve　with　frequency　impedances　measured　off　at　hundreds　of　sample　points.　Afterwards,　the　corresponding　passive　equivalent　broadband　circuit　is　built　via　passive　algorithm　and　synthesis　procedure.　The　applicability　of　the　method　to　our　model　is　confirmed　by　comparing　the　simulated　and　measured　data.　The　double　exponential　model　parameters　of　overvoltage　are　calculated　according　to　the　definition　of　International　Electrotechnical　Commission　(IEC)　and　the　voltage　distribution　of　the　valve　module　composed　of　the　key　components　is　characterized,　in　favor　of　which　the　key　components　can　be　optimized.　©　2019　IEEE.