Titanium　alloys　are　widely　applied　in　the　aerospace　field　owing　to　their　exceptional　properties,　but　coarse　grains　can　easily　form　during　the　welding　process,　seriously　diminishing　the　mechanical　properties　of　the　welded　joint.　To　address　this　problem,　a　pulsed　current　was　introduced　to　refine　the　grain　structure　of　titanium　alloy　welds.　In　this　study,　we　investigated　the　effect　of　varying　the　pulsed　current　frequency　on　grain　refinement　in　titanium　alloy　welds　and　explored　the　mechanism　of　grain　refinement　using　the　＂overlap　welding＂　method.　The　results　showed　that　the　grain　refinement　improved　with　increasing　pulse　current　frequency,　particularly　at　the　original　&　beta;　and　&　alpha;　grain　boundaries.　Compared　to　non-pulsed　welding,　the　original　&　beta;　grain　boundary　decreased　from　305　to　158　&　mu;m,　and　the　maximum　&　alpha;　grain　size　decreased　from　93.236　to　46.693　&　mu;m　when　the　pulse　frequency　was　100　Hz.　Moreover,　dendrite　fragmentation　was　identified　as　the　primary　mechanism　of　grain　refinement　in　pulsed　plasma　arc　welding　of　the　Ti6Al4V　alloy.　The　repeated　heating　of　the　molten　pool　by　application　of　the　pulsed　current　caused　the　dendrite　tip　to　remelt　in　the　pasting　region,　promoting　dendrite　fragmentation.