Nucleate pool boiling heat transfer data of the HC170/HFC23 system have been systematically measured in a wide range of pressures and heat fluxes. The experimental results are also compared with the measured data of R503 and R508B. It is found that the heat transfer coefficient of HC170/HFC23 system at the azeotropic concentration of (HC170/HFC23=0.582/0.418) is higher than that of R508B system and approximately is equal to that of R503 system. Furthermore, the experimental results are compared with the calculated values using a modified Jungnickel correlation. The comparison between all calculated values and experimental data shows a good agreement. The mean deviation is within ±8%.