This article is a pridiction of the activity coefficients of HCl in a series of MeOH-H_2O, EtOH-H_2O, HAc-H_2O and Dioxane-H_2O mixtures by the mean sphere approximation(MSA). By comparing the results of MSA with those calculated from Pitzer's equation or from literatures in the MeOH-H_2O media, it is shown that the MSA is powerful in the aqueous-nonaqueous media although it takes the diameter of cation as the only adjustable parameter. A disscusion about the results and the diameter of H~+ in each medium is given at the end briefly.