This study uses high pressure single gas (He and N2) and mixture(He + N2) gas instead of the high pressure syngas , and the test pressure for each gas were from 0.5 MPa to 3 MPa with test temperature from 150 ℃ to 450 ℃. The results show that the working pressure, gas composition and flow heating methods influence the high pressure gas convective heat transfer coefficient, and the effect of the working pressure is the most prominent. The average convection heat transfer coefficients are obtained for different kinds of high pressure gas in annular channel heat exchanger, and the correlations of the typical flow heating methods and its applicable condition.