Vortex　tube　(VT)　is　a　simple　energy　separating　device　which　is　compact　and　simple　to　produce　and　to　operate.　Although　intensive　research　has　been　carried　out　in　many　countries　over　the　years,　the　efficiency　is　still　low.　In　order　to　improve　the　energy　separate　efficiency　of　vortex　tubes,　three　innovative　technologies　were　applied　to　vortex　tubes.　A　new　nozzle　with　equal　gradient　of　Mach　number　and　a　new　intake　flow　passage　of　nozzles　with　equal　flow　velocity　were　designed　and　developed　to　reduce　the　flow　loss.　A　new　kind　of　diffuser　invented　by　us　was　installed　for　reducing　friction　loss　of　air　flow　energy　at　the　end　of　the　hot　end　tube　of　vortex　tube,　which　can　greatly　improve　the　performance　of　vortex　tube.　The　experiment　results　indicated　that　these　modifications　could　remarkably　improve　the　performance　of　vortex　tube.　The　developed　vortex　tube　was　not　only　superior　to　the　conventional　vortex　tube　but　also　superior　to　that　made　by　two　companies　in　world　under　big　cold　gas　mass　flow　ratio.　(c)　2007　Elsevier　Ltd　and　IIR.　All　rights　reserved.