©　2017　IEEE.　High　voltage　circuit　breakers　are　most　important　protective　device　in　power　system.　Dynamic　contact　resistance　measurement　(DRM)　is　considered　to　be　an　effective　assessment　technique　for　contact　ablation　which　has　been　widely　used　for　many　years.　However,　the　contact　resistance　curves　will　be　influenced　by　many　factors,　such　as　injected　current　and　velocity.　In　power　systems,　circuit　breakers　often　work　under　non-normal　conditions,　like　the　fatigue　of　spring　and　the　insufficient　of　hydraulic　pressure.　These　conditions　will　decrease　the　opening　velocity　and　then　greatly　affect　the　stability　of　the　curve　as　well　as　the　average　contact　resistance　during　the　DRM　tests.　Based　on　collecting　the　contact　resistance　curves　in　different　opening　velocities,　it　is　found　that　the　values　of　contact　resistance　increase　with　the　growing　of　the　opening　velocity.　Opening　velocity　will　affect　the　frictional　heat　and　effective　contact　area　of　the　contact,　and　the　two　factors　are　discussed　by　the　finite　element　model　and　micro　measurement　in　this　paper.　The　finite　element　simulation　model　can　be　used　to　prove　that　the　frictional　heat　can　be　ignored,　while　the　contact　resistance　with　different　velocities　is　determined　by　the　changing　of　effective　contact　area.