Abstract: A method of measuring the enthalpy of China's No.3 jet fuel RP-3 at supercritical pressure was proposed based on the principle of energy conservation.At the same time,the enthalpy of RP-3 at different supercritical pressures between 323K and 834K was measured.The results indicate that,the enthalpy of RP-3 at different pressures is almost the same when the fuel temperature is lower than its critical temperature.When the fuel temperature is higher than its critical temperature,the difference of enthalpy at different supercritical pressures declines with the growing pressure.In addition,the temperature of RP-3 calculated by the curve of enthalpy had been compared with the measurement value,showing that the measurement of enthalpy is accurate and reliable.At last,the influence of heat flux on heat transfer of RP-3 was studied.The test results indicate that the Nusselt number increases with heat flux if the bulk fuel temperature Tb/Tc is lower than 1.179(760K).