The　basic　organic　flash　cycle　(BOFC)　system　has　difficulty　in　achieving　the　high　system　efficiency　due　to　the　great　exergy　destruction　of　the　throttling　process.　To　reduce　the　energy　loss　and　increase　the　BOFC　system＇s　efficiency,　three　improved　systems　including　the　regenerative　organic　flash　cycle　(ROFC)　system　and　two　novel　organic　flash　Rankine　cycle　(OFRC)　systems　were　presented　in　this　work.　Thermodynamic　analysis　including　energy,　exergy　and　economic　analysis　were　conducted　to　evaluate　the　performance　of　the　system,　and　system　optimization　based　on　the　particle　swarm　optimization　(PSO)　algorithm　was　performed　to　indicate　the　development　potential　of　the　system.　In　addition,　performance　comparison　between　four　OFC　systems　and　the　basic　organic　Rankine　cycle　(BORC)　system　was　also　carried　out.　Obtained　results　showed　that　the　largest　exergy　destruction　of　both　the　BOFC　system　and　the　ROFC　system　was　caused　by　the　throttling　process,　while　the　biggest　energy　loss　of　the　two　OFRC　systems　was　caused　by　the　heat　transfer　process　in　the　heat　recovery　unit.　Compared　with　the　ROFC　system　and　the　OFRC-I　system,　the　OFRC-II　system　was　considered　to　be　the　most　promising　solution　in　enhancing　the　performance　of　the　BOFC　system.　Finally,　optimization　results　showed　that　the　OFRC-II　system　had　the　higher　global　thermal　and　exergy　efficiencies,　compared　to　the　BORC　system.　©　2020　Elsevier　Ltd