In　this　study,　the　oil　droplets　separation　process　in　a　swirling　flow　was　investigated　using　numerical　simulations　and　verification　experiments.　Numerical　models　were　established　to　investigate　the　effects　that　the　collision　and　breakup　of　droplets　and　the　collision　between　droplets　and　wall　on　separation　efficiency,　respectively.　The　separation　efficiencies　were　calculated　using　different　models　under　various　inlet　velocities,　from　10　to　18　m/s.　The　simulated　results　showed　that　droplets　colliding　could　improve　the　separation　efficiencies　with　up　to　22.4%　increments　at　the　10　m/s　inlet　velocity　for　droplets　with　a　diameter　of　10　mu　m.　The　oil-gas　separation　efficiency　was　reduced　up　to　17.4%　due　to　the　oil　droplet-wall　interaction　in　swirling　flow　when　the　simulation　model　involved　droplet-wall　collisions.　The　simulated　separation　efficiencies　showed　little　change　when　oil　droplet　breakups　were　considered　in　the　model　under　different　inlet　velocities　and　droplet　diameters.　A　test　rig　was　built　to　validate　the　simulation　results.　It　showed　good　agreement　between　the　experimental　data　and　simulated　results.　Thus,　the　numerical　simulation　model　could　be　used　to　predict　separation　performance　and　understand　the　separation　process　in　a　swirling　flow.　(C)　2016　Institution　of　Chemical　Engineers.　Published　by　Elsevier　B.V.　All　rights　reserved.