The　traditional　classification　of　working　fluid,　which　is　based　on　the　characteristics　of　saturated　vapor　curve　in　temperature-entropy　(T-s)　diagram,　focuses　more　on　the　output　power　of　organic　Rankine　cycle　(ORC).　The　performance　of　an　ORC　is　greatly　influenced　by　pump　power　consumption,　which　is　closely　related　to　the　subcooled　region　and　saturated　liquid　curve　of　the　working　fluid.　This　paper　proposes　a　new　classification　method　of　working　fluids,　which　simultaneously　considers　the　curved　triangle　area　in　subcooled　region　(A1),　the　slope　of　saturated　liquid　curve　(k),　and　the　pump　power　consumption　(wp).　It　is　discovered　that　dry　working　fluids　have　a　larger　area　of　curved　triangle　in　subcooled　region　and　higher　pump　power　consumption　compared　to　isentropic　working　fluids.　Among　all　the　dry　or　isentropic　working　fluids　studied,　halogenated　hydrocarbons　have　the　steepest　slope　of　saturated　liquid　curve.　The　more　silicon　in　siloxane,　the　larger　the　values　of　A1　and　k,　however,　the　smaller　the　value　of　wp.　On　this　basis,　the　ratio　of　the　curved　triangle　area　in　subcooled　region　(A1)　to　the　curved　triangle　area　in　superheated　region　(A2),　which　is　(A1:A2),　is　used　to　evaluate　the　working　fluid　characteristics.　Additionally,　the　ratio　of　the　net　output　power　(wnet)　to　the　condenser　load　(qc),　which　is　(wnet:　qc),　is　used　to　evaluate　the　ORC　performance.　It　can　be　determined　that　D5　(decamethylcyclopentasiloxane)　and　MD4M　(tetradecamethylhexasiloxane)　may　be　the　essential　working　fluids　for　future　ORC　design　and　operation.