Thermophysical　properties　of　an　organic　working　fluid　greatly　influence　the　thermodynamic　performance　of　an　Organic　Rankine　Cycle　(ORC).　Temperature-entropy　(T-s)　diagram　is　a　useful　and　common　tool　used　for　analyzing　thermodynamic　state　transition　of　working　fluid　and　cycle　performance.　In　a　temperature-entropy　(T-s)　diagram,　four　areas　are　defined　in　the　evaluation　method　proposed　in　this　paper.　The　ratio　of　two　areas,　which　are　a　curved　triangle　in　near-critical　region　and　a　curved　trapezoid　in　two-phase　region,　is　used　to　evaluate　the　characteristics　of　working　fluid.　The　ratio　of　the　other　two　areas,　which　are　a　hexagon　representing　net　output　work　of　cycle　and　a　rectangle　representing　the　net　output　work　of　the　Carnot　cycle,　is　used　to　evaluate　the　cycle　performance.　On　this　basis,　a　comprehensive　evaluation　indicator　that　evaluates　the　characteristics　of　working　fluid　and　the　cycle　performance　simultaneously　is　established　by　dividing　the　above　two　ratios.　Using　the　proposed　method,　dry　and　isentropic　organic　working　fluids,　which　are　often　used　in　an　Organic　Rankine　Cycle,　are　evaluated　comprehensively.　The　evaluation　method　proposed　in　this　paper　may　provide　a　reference　for　the　design　and　actual　operation　of　Organic　Rankine　Cycle　system.