Considering　the　degradation　of　the　mechanical　properties　of　steel　and　concrete　under　high　temperature　and　the　strain　rate　effect　of　the　materials,　a　mesoscopic　numerical　analysis　model　of　reinforced　concrete　beam　are　proposed　based　on　the　meso-structure　of　concrete.　The　influences　of　fire　duration　time　and　impact　energy　on　the　impact　resistance　behavior　of　concrete　beams　in　fire　are　discussed.　In　this　paper,　the　failure　process　of　reinforced　concrete　beam　subjected　to　impact　load,　the　impact　force　time　history,　the　reaction　time　of　support　and　the　displacement　response　in　the　middle　span　are　analyzed.　The　results　show　that　the　mesoscopic　numerical　model　can　well　simulate　the　heat　transfer　process　of　each　components　of　concrete.　With　the　increase　of　heating　time,　the　concrete　beam　under　the　impact　load　is　more　serious,　meanwhile　the　duration　of　the　impact　force　and　the　maximum　displacement　of　the　span　increase,　but　the　impact　force　peak　decreases;　with　the　increase　of　impact　energy,　the　shear　failure　of　concrete　beam　is　more　serious,　and　the　impact　force　peak　increases.　The　maximum　displacement　increases　linearly　with　the　impact　energy.　©　2018,　Science　Press.　All　right　reserved.