to　high　voltage　and　current　levels　of　high　voltage　DC　(HVDC)　relays　and　the　absence　of　natural　zero　crossings　in　DC　system,　the　arc　generated　during　the　breaking　process　of　the　relay　has　high　energy　and　is　difficult　to　extinguish,　which　affects　the　relay＇s　breaking　reliability　and　electrical　life.　In　order　to　accelerate　arc　extinguishing,　the　permanent　magnets　are　usually　placed　in　the　arc　extinguishing　chamber　of　the　HVDC　relay.　The　existing　simulation　analysis　is　mostly　based　on　the　uniform　distribution　of　the　magnetic　field,　while　the　distribution　of　the　magnetic　field　generated　by　the　permanent　magnets　is　non-uniform.　Therefore,　based　on　the　theory　of　magnetohydrodynamics　(MHD),　this　paper　establishes　the　numerical　model　of　arc　plasma　and　permanent　magnets　of　HVDC　relay　by　means　of　COMSOL　Multiphysics　software,　analyzes　the　arc　motion　characteristics　under　the　action　of　non-uniform　magnetic　field　generated　by　permanent　magnet.　The　results　of　the　simulation　analysis　will　provide　a　basis　for　the　application　of　permanent　magnets　in　HVDC　relays.　©　2021　IEEE.