Organic　Rankine　cycle　(ORC)　system　has　been　widely　used　in　industries　due　toits　superior　performance.　The　working　fluid　pump,　providing　the　mass　flow　rate　and　the　evaporation　pressure　of　the　ORC　system,　is　one　of　important　components　in　the　system.　In　addition,　the　performance　of　working　fluid　pumps　also　has　significant　effects　on　the　component　and　overall　system　performance.　In　this　paper,　the　effects　of　different　thermal　parameters　on　the　pump　electric　power　input　of　unit　mass　flow　and　back　work　ratio　(BWR)　were　analyzed.　Furthermore,　the　experiment　was　conducted　under　simulative　ORC　conditions　by　using　R245fa　and　condensing　temperature　of　303K.　The　experimental　operating　characteristics　of　two　different　types　of　working　fluid　pumps　(multistage　centrifugal　pump　and　hydraulic　diaphragm　metering　pump)　were　analyzed　and　its　effects　on　the　performance　of　ORC　system　were　presented.　Results　showed　that　the　mass　flow　rate　delivered　by　the　hydraulic　diaphragm　metering　pump　was　low　and　was　not　significantly　affected　by　the　variation　of　outlet　pressure.　The　maximum　electric　power　input　was　only　360.34W,　which　was　16.29%　of　the　multistage　centrifugal　pump.　Their　actual　operation　efficiency　changes　with　operating　conditions　were　up　to　59.96%　and　55.26%,　respectively.　By　the　theoretical　calculation,　the　BWR　for　the　ORC　system　using　the　two　pumps　varied　between　0.03　and　0.48.　And　the　maximum　thermal　efficiency　could　reach　up　to　11.66%,　10.35%,　respectively.　The　hydraulic　diaphragm　metering　pump　is　more　suitable　to　the　low　mass　flow　ORC　system.　©　2019,　Chemical　Industry　Press.　All　right　reserved.