The　potential　of　accidental　loads　such　as　explosions　and　impacts　cannot　be　overlooked　given　the　widespread　use　of　precast　concrete　(PC)　buildings.　However,　research　on　the　impact　resistance　of　reinforced　concrete　precast　beams　is　limited.　In　order　to　explore　the　dynamic　behavior　of　PC　beams　connected　by　grouted　sleeves　under　impact　loads,　this　work　developed　a　numerical　model　based　on　the　finite　element　program　LS-DYNA.　First,　the　experimental　process　was　described　in　detail,　and　the　numerical　model　was　evaluated　and　calibrated　according　to　the　experimental　data.　Then,　parameters　such　as　impact　location,　concrete　strength　of　precast　section　and　stirrup　rate　of　cast-in-place　area　were　studied.　Finally,　a　simpler　model　based　on　equal　high-frequency　impulse　impact　force　was　suggested,　and　the　viability　of　a　single-degree-of-freedom　model　theory　was　proved　for　the　dynamic　analysis　of　PC　simply　supported　beams　subjected　to　impact　loading.　According　to　the　findings,　the　interface　of　precast　concrete　and　cast-in-place　concrete　is　the　weak　point　of　the　PC　beam,　which　is　prone　to　shear　damage　under　impact　loads.　Second,　when　the　middle　of　the　cast-in-place　part　of　the　PC　beam　is　impacted,　wide　cracks　from　the　bottom　to　the　top　are　quite　likely　to　form.　As　a　result,　the　most　disadvantageous　impact　position　for　PC　beams　is　in　the　middle　of　the　cast-in-place　portion.　Although　increasing　the　concrete　strength　of　the　precast　section　can　reduce　crack　formation,　it　has　minimal　influence　on　the　interface＇s　shear　resistance.　Furthermore,　increasing　the　stirrup　rate　in　the　post-cast　portion　can　increase　the　overall　shear　resistance　of　the　PC　beams.