This paper reports the results of solubility calculation of the phase system HCl- NaCl- H2O at 25℃ whenθ HNa (interactions of two species with the same charge) andΨ HNaCl (interactions of three species) were changed by＋ 10％ and－ 10％ . The results indicated that the effects of the two kinds of interactions on the calculated solubility of the system were regular. The calculated solubilities of the system did not vary while the two interactions were increased and decreased simultaneously. The solubility data of the system changed greatly as one interaction was increased and the other decreased. This study is significant for the chemical technology of salting out salts from the water- salt system.