Abstract: By carrying out experimental study on the condensation of steam with air on the outer wall of a vertical pipe, the effects of mass fraction of air, pressure and subcooling on steam condensation were analyzed, and the empirical correlations of condensation heat transfer of steam with the air were given. The results show that under the same air mass fraction and pressure conditions, the effect of wall subcooling on condensation heat transfer coefficient is greater than that of the pure steam condensation given by Nusselt laminar solution. The empirical correlation obtained is suitable for a wider application region and the correlation error associated with the experimental value is within ±10%.