Experiments have been carried out for steady turbulent-flow film boiling of subcooledliquid R11 flowing upward in a vertical circular tube with velocities in a range of 1 .3-4.9m/s and liquid temperatures subcooling in a range of 16.2-32 .5℃. The exponent ofRein a semi-empirical expression is determined as m = 0.65 from the experimental dataobtained, which coincides with the theoretical value m = 2/3 reported previously. Mean-while, the modified semi-empirical theory is verified and further discussed, and the onlyempirical constant c is determined as 5.4 ×10.