The　impact　velocities　of　hammer　crusher　directly　affect　the　crushing　effect　of　rock.　In　order　to　study　influence　of　impact　velocities　of　hammer　head　on　the　crushing　effect　and　utilization　efficiency　of　fracture　energy　in　green　sandstone,　macroscopic　and　microscopic　mechanical　response　relationship　of　green　sandstone　was　established　by　combining　with　physical　experiments　and　microscopic　parameter　calibration.　The　characteristics　of　stress　chain,　characteristics　of　damage　and　degradation,　acoustic　emission　and　changes　of　crack　in　green　sandstone　under　different　impact　velocities　of　hammer　crusher　were　analyzed　using　particle　flow　code,　and　the　utilization　efficiency　of　fracture　energy　was　studied.　The　results　show　that:　①　During　the　crushing　process　of　green　sandstone,　the　internal　part　of　destructive　micro-unit　is　mainly　composed　of　tension　chain,　and　the　edge　of　failure　is　mainly　composed　of　pressure　chain.　In　the　undamaged　micro-unit,　the　pressure　chain　and　tension　chain　cross　each　other　to　form　network.　The　tension　chain　cause　extension　of　crack,　and　the　final　failure　is　the　result　of　the　combined　action　of　pressure　chain　and　tension　chain.　②　The　failure　pattern　of　green　sandstone　is　divided　into　the　stage　of　local　failure,　extended　failure,　and　intensified　failure.　The　number　of　destructive　micro-unit　is　divided　into　the　stage　of　rapid　increase,　gradual　slowing,　and　stabilization.　The　larger　the　impact　velocities,　the　greater　the　stable　increase　in　the　number　of　destructive　micro-unit,　and　the　number　of　destructive　micro-unit　approximately　follows　linear　distribution　with　the　impact　velocities.　③　With　the　increase　of　impact　velocities,　the　cumulative　number　of　crack　in　green　sandstone　is　divided　into　the　stage　of　rapid　increase　and　stabilization.　In　the　stage　of　crack　initiation,　shear　crack　are　the　main　type,　and　the　initial　input　energy　is　mainly　used　for　the　generation　of　shear　crack,　while　the　proportion　of　tensile　crack　gradually　increases,　and　eventually　tensile　crack　are　the　main　type.　④　During　the　failure　process　of　green　sandstone,　the　fracture　energy　can　be　divided　into　the　stage　of　rapid　increase,　gradual　slowing,　and　stabilization.　The　utilization　efficiency　of　fracture　energy　can　be　divided　into　the　stage　of　rapid　increase,　slow　increase,　and　slow　decrease,　with　the　maximum　value　of　10.851%,　and　the　quantitative　relationship　between　utilization　efficiency　of　fracture　energy　and　impact　velocities　is　established.　The　result　of　the　study　not　only　provide　preliminary　exploration　of　the　crushing　effect　and　utilization　efficiency　of　fracture　energy　in　green　sandstone　from　microscopic　perspective,　but　also　provide　reference　for　the　reasonable　selection　of　process　parameters　in　the　crushing　process　of　hammer　crusher.　©　2024　China　Coal　Society.　All　rights　reserved.