The real gas effect was not taken into account in the current nucleation models, which will cause relatively big errors in the simulation of condensation process, and the supersonic condensation characteristics in the nozzle are still not clear now. Therefore, the fugacity is introduced into the model to increase the calculation accuracy of nucleation rate. Based on the modified model, the supersonic condensation process of the methane-ethane binary mixture was studied to clarify the nucleation and droplet growth process. Then the condensation characteristics of natural gas with different operation parameters were analyzed. The results show that in the condensation process of methane-ethane binary mixture, the ethane vapor first reaches critical radius and breaks through the free energy barrier and serve as the condensation nuclei for methane and ethane gas. The latent heat of condensation plays a dominant role in the change of the droplet growth rate of the binary mixture. Higher pressure or lower temperature or higher ethane content will result in greater nucleation rate and humidity. (C) 2018 Elsevier Ltd. All rights reserved.