In　this　study,　the　1991　rock　avalanche,　in　Touzhai,　Zhaotong,　Yunnan,　China,　was　considered　the　study　object.　The　investigation　of　the　landslide　accumulation　body　revealed　that　the　Touzhai　rock　avalanche　accumulation　body　has　the　characteristics　of　wide　gradation　and　poor　sorting.　A　combination　of　field　investigations,　indoor　and　outdoor　experiments,　and　numerical　simulations　were　used　to　invert　the　occurrence　and　spreading　range　of　rock　avalanche-debris　flow　hazards.　To　invert　and　analyze　its　dynamics　and　the　crushing　process,　a　three-dimensional　discrete　element　modeling　was　performed　on　the　real　terrain　data.　Simulation　results　showed　that　the　movement　time　of　the　numerically　simulated　Touzhai　rock　avalanche　was　approximately　200　s.　After　50　s　of　movement,　the　peak　velocity　reached　32　m/s,　and　the　velocity　gradually　decayed　after　the　sliding　mass　rubbed　violently　against　the　valley　floor　and　collided　with　the　mountain.　Due　to　the　meandering　nature　of　the　gully,　the　sliding　mass　makes　its　way　down　the　gully　and　constantly　collides　with　the　mountain,　making　particles　appear　to　climb,　with　some　particles　being　blocked　by　the　valley.　After　150　s　of　movement,　the　average　velocity　rate　decreased　substantially,　and　the　landslide-avalanche　debris　reached　the　mouth　of　the　trench.　After　200　s　of　movement,　the　average　sliding　velocity　tends　to　0　m/s,　where　the　avalanche　debris　tends　to　stop　and　accumulate.　When　the　rock　avalanche　movement　reaches　the　mouth　of　the　gully,　the　avalanche　debris　spreads　to　the　sides　as　it　is　no　longer　bounded　by　the　hills　on　either　side　of　the　narrow　gully,　eventually　forming　a　‘trumpet-shaped’　accumulation,　and　the　granular　flow　simulation　matched　the　findings　of　the　landslide　site　accumulation.　©　2023　by　the　authors.