Experimental model of the heat transfer characteristics of the passive residual heat removal heat exchanger (PRHR HX)was built and experiments were performed. The tank fluid rose gradually which lead to a thermal stratification phenomenon. Comparisons of different correlation in literatures with the experimental data were carried out. The errors between the theoretical of Dittus Boelter correlation and experimental heat transfer coefficient of the tube inside single phase heat transfer is 0.35%. For the tube outside natural convection, the errors of McAdams correlations reach about 0.55% for the horizontal region and 3.28% for the vertical region. The best estimate fit correlation for tube inside single phase convection is Dittus Boelter correlation and the tube outside natural convection heat transfer correlations are McAdams correlations.