In　this　paper,　the　thermodynamic　and　thermoeconomic　performance　of　an　ORC　system　with　pure　working　fluids　and　their　zeotropic　mixtures　each　having　different　critical　temperatures　are　compared.　Two　high　critical　temperature　(toluene　and　decane)　and　two　low　critical　temperature　(R245fa　and　R123)　working　fluids　as　well　as　their　zeotropic　mixtures　are　considered.　The　effects　of　four　parameters　including　evaporation　temperature,　condensation　temperature,　superheat　degree　and　mass　fraction　of　the　zeotropic　mixtures　on　the　thermodynamic　and　thermoeconomic　performances　of　the　ORC　system　are　investigated.　The　multi-objective　optimization　based　on　genetic　algorithm　is　conducted　to　reveal　the　optimal　performances　of　the　ORC　system.　The　results　show　that　high　critical　temperature　working　fluids　and　their　zeotropic　mixtures　possess　better　thermodynamic　and　thermoeconomic　performances,　however,　the　zeotropic　mixtures　do　not　improve　the　thermodynamic　and　thermoeconomic　performances　obviously.　Furthermore,　the　zeotropic　mixtures　at　the　mass　fraction　of　0.9　toluene/0.1　decane　have　the　best　thermoeconomic　performance.　The　zeotropic　mixtures　can　significantly　reduce　the　heat　transfer　area　of　the　heat　exchangers　under　high　evaporation　temperature　condition.　In　addition,　the　multi-objective　optimization　indicates　that　the　optimal　evaporation　temperature　approaches　its　upper　bound　while　the　optimal　condensation　temperature　and　superheat　degree　almost　close　to　their　lower　bounds.