In　this　paper,　cycle　efficiency,　net　electric　power　and　steam　lose　rate　are　calculated　between　the　single　flash　and　binary　geothermal　power　system.　The　prime　mover　is　10kW　single　screw　expander.　These　parameters　of　the　single　flash　system　are　calculated　by　rated　inlet　volume　flow　rate　of　the　single　screw　expander.　The　heat　absorption　capacity　of　both　systems　is　determined　to　be　equivalent.　The　working　fluids　of　binary　system　are　R134a,　R245fa,　and　R600a.　Those　parameters　of　binary　system　are　calculated　with　the　condition　that　the　saturated　temperature　of　the　working　fluid　before　pump　is　22　C.　Engineering　Equation　Solver　(EES)　software　is　used　for　analysis.　The　results　show　that　electric　power　of　the　single　flash　system　is　on　the　rise　and　steam　loss　rate　of　the　single　flash　system　is　on　the　decrease　with　an　increase　of　the　inlet　temperature　between　100　degrees　C　and　155　degrees　C.　From　the　same　heat　absorption　capacity,　the　binary　system　has　apparent　improvement　in　electric　power　and　efficiency.　The　efficiency　of　binary　system　can　increase　by　2.1%　compared　with　single　flash　system.