This　paper　presents　an　experimental　study　on　the　dynamic　compressive　behaviors　of　concrete　confined　with　unidirectional　natural　flax　fiber　reinforced　polymers　(FFRPs)　under　an　axial　impact　load.　A　total　of　80　specimens　were　prepared　and　tested　using　a　75　mm　diameter　split　Hopkinson　pressure　bar　(SHPB)　at　different　strain　rates　varying　from　50　to　200　s−1.　The　experimental　results　showed　that　the　failure　modes　and　dynamic　compressive　mechanical　properties　(i.e.,　dynamic　compressive　strength,　critical　compressive　strain,　and　energy　absorption　capacity)　of　FFRP-confined　concrete　were　sensitive　to　the　strain　rate.　The　unconfined　concrete　specimens　were　crushed　into　small　pieces　at　relatively　low　strain　rates,　whereas　the　FFRP-confined　concrete　specimens　failed　with　FRP　rupture　and　partial　damage　to　the　core　concrete　at　relatively　high　strain　rates.　This　indicates　that　the　confinement　of　FFRP　jackets　can　alleviate　concrete　damage　and　improve　impact　resistance.　Compared　with　unconfined　concrete,　the　application　of　the　FFRP　jacket　remarkably　improves　the　compressive　strength,　critical　strain,　and　toughness,　which　indicates　outstanding　impact　resistance.　Increasing　the　confinement　stiffness　of　the　FFRP　contributed　to　increasing　the　compressive　strength,　critical　strain,　and　toughness.　Based　on　the　experimental　results,　the　confinement　mechanism　of　external　flax　FRP　jackets　on　concrete　was　discussed,　and　a　new　dynamic　strength　model　was　proposed　to　predict　the　dynamic　compressive　strength　of　FFRP-confined　concrete　within　the　investigated　strain　rate　range.　©　2020