Abstract: Pressure influence characteristic of the steam condensation in presence of non-condensable gas on vertical wall is important in the transient regulation of the gas-steam pressurizer in the integrated pressurized water reactor and the progress of the residual heat removing in the compact containment, and it is quite rare in the public researches. Based on the mass and heat analogy method, the improved diffusion layer model suitable for high pressure was developed to access to the pressure influence characteristic of the steam condensation in presence of non-condensable gas on vertical wall. It is indicated that compared with the experiment result, the improved model can get good applicability and accuracy in the low and moderate pressure region. The increase of the total pressure enhances the condensation heat transfer, and this enhanced trend decreases with the increase of total pressure. In the low and moderate pressure region (0.1-7.0 MPa), there is a demarcation point (p_c) of the total pressure corresponding to the influence on the condensation heat transfer. It is the pressure sensitive region (0.1 MPa p_c) when the total pressure is less than the demarcation point, and the high pressure region (p_c 7.0 MPa) that total pressure is higher than the demarcation point is the pressure un-sensitive region. At the same time, the variety of non-condensable gas and the concentration of non-condensable gas play an important role in the heat transfer process of steam condensation on vertical wall and these effects are investigated in the paper. The diffusion coefficient of non-condensable gas is further analyzed to explain the difference caused by non-condensable gas.