The　circulation　pump　in　an　organic　Rankine　cycle　(ORC)　increases　the　pressure　of　the　liquid　working　fluid　from　low　condensing　pressure　to　high　evaporating　pressure,　and　the　expander　utilizes　the　pressure　difference　to　generate　work.　A　portion　of　the　expander　output　power　is　used　to　offset　the　consumed　pumping　work,　and　the　rest　of　the　expander　power　is　exactly　the　net　work　produced　by　the　ORC　system.　Because　of　the　relatively　great　theoretical　pumping　work　and　very　low　efficiency　of　the　circulation　pump　reported　in　previous　papers,　the　characteristics　of　the　expander　power　used　for　offsetting　the　pumping　work　need　serious　consideration.　In　particular,　the　present　work　examines　those　characteristics.　It　is　found　that　the　characteristics　of　the　expander　power　used　for　offsetting　the　pumping　work　are　satisfactory　only　under　the　condition　that　the　working　fluid　absorbs　sufficient　heat　in　the　evaporator　and　its　specific　volume　at　the　evaporator　outlet　is　larger　than　or　equal　to　a　threshold　value.