The　present　study　provided　a　preliminary　investigation　on　the　kinetic　and　fragmentation　characteristics　of　the　Xuzha　rock　avalanche,　a　ridge-top　rock　avalanche　located　in　the　southeast　of　the　Tibetan　Plateau,　China.　Field　investigation　revealed　that　the　Xuzha　rock　avalanche　originated　from　a　steep　slope　and　caused　the　tributary　of　the　Jinsha　River　dammed,　showing　an　extreme　high　mobility.　The　vertical　profile　of　avalanche　debris　showed　that　it　experienced　intensive　fragmentation　during　transport.　To　back-analyze　its　kinetic　and　fragmentation　processes,　the　discrete　element　modeling　was　conducted.　Simulation　results　suggested　that　the　Xuzha　rock　avalanche　lasted　about　80 s　and　had　a　maximum　velocity　of　~　73 m/s,　about　1.5　times　the　highest　average　velocity　(48 m/s).　The　travel　distance　and　the　thickness　of　the　deposits　matched　well　with　the　field　observations.　Notable　features　including　the　preservation　of　the　original　positional　order　and　the　inverse　vertical　grading　of　avalanche　debris　obtained　from　the　simulation　were　consistent　with　the　field　observations.　The　statistical　results　of　fragments　showed　that　the　fragment　size　distributions　could　be　described　by　Weibull　distribution.　In　general,　with　the　landslide　propagation,　the　size　of　fragments　gradually　decreased　and　the　fragment　size　distribution　became　narrower.　Further,　dynamic　fragmentation　continuously　occurred　with　the　landslide　propagation,　generating　an　abundance　of　fine-grain　particles　which　behaved　as　interstitial　granular　fluids　between　coarse　particles.　Finally,　we　inferred　that　dynamic　rock　fragmentation　and　fine　particle　fluidization　were　the　reasonable　explanations　for　the　high　mobility　of　the　Xuzha　rock　avalanche.　©　2021,　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.