Aiming to make a suitable selection of the working fluids for Ocean thermal energy conversion(OTEC) power generation organic Rankine cycle,the PR equation of state was adopted to calculate the thermal performances of OTEC organic Rankine cycle using each of eleven dry fluids.The following conclusions were drawn: as the critial temperature of the selected fluid increases,the thermal efficiency of the Rankine cycle will rise as a whole.Fluid R600 exhibits considerably high values of thermal efficiency,meanwhile,the evaporation pressure and the condensation pressure are in the appropriate range.It is likely to be the most promising fluid for OTEC organic Rankine cycles.