A physical and revised mathematical droplet model was proposed for condensation heat transfer process near the cooled solid surface,according to the micro-physical mechanism and thermodynamic characteristics in condensation phase change process. The heat transfer model considering the effect of interfacial effects was used to calculate the temperature of clusters. The mathematical model based on the refined DM homogeneous nucleation model,introducing the wall conditions and making some correlations,was used to calculate the size distribution of clusters,and also describe the effect of the presence of non-condensable gases on the distribution of clusters. The present model explains quantitatively the fact that the presence of small amount of non-condensable gases deteriorate condensation heat transfer performance significantly. The predicted results of the model agree with the experimental results reported in the literature.