A　two　species　amensalism　model　with　Beddington–DeAngelis　functional　response　is　proposed　and　studied　in　this　paper.　The　existence　and　stability　of　possible　equilibria　are　investigated.　Under　some　additional　assumptions,　there　are　two　stable　equilibria　which　implies　this　system　is　not　asymptotically　stable.　Based　on　the　stability　analysis　of　equilibria,　closed　orbits　and　the　saddle　connection,　we　give　some　comprehensive　bifurcation　and　global　dynamics　of　the　system.　Next,　we　further　incorporate　the　Allee　effect　into　the　second　species　and　provide　a　complete　qualitative　and　bifurcation　analysis　of　the　system　with　Allee　effect.　Numerical　simulations　show　that　the　system　with　an　Allee　effect　must　take　a　longer　time　to　reach　its　stable　steady-state　solution　than　that　without　Allee　effect.　There　is　a　good　agreement　between　the　present　results　and　the　numeric　simulations.　©　2019　Elsevier　Ltd