The salt-water interactions on single salt aqueous solutions of cesium sulfate and cesium chloride, as well as their mixing solutions, have been investigated by a combination of density measurements by an Anton Paar Digital vibrating-tube densimeter and the correction of the Pitzer model of electrolyte. The volumetric properties including apparent molar volume (Vϕ) and the coefficient of thermal expansion of the solution (α) of the binary systems (CsCl + H2O), (Cs2SO4 + H2O) and the ternary system (CsCl + Cs2SO4 + H2O) from 283.15 to 363.15 K at 5 K intervals and atmospheric pressure were derived. Variation trends of these volumetric properties against temperature and molality were revealed minutely. The Pitzer single salt parameters (βMX0v, βMX1v and CMXv, MX = CsCl and Cs2SO4), mixing ion-interaction parameters (θCl,SO4v and ψCs,Cl,SO4v) as well as the correlation coefficient ai in the temperature-dependence equation (F(i, p, j) = a1 + a2ln(T/298.15) + a3(T-298.15) + a4/(620-T) + a5/(T-227)) have been obtained according to Pitzer ion-interaction model of electrolytes. These results are helpful to understanding the ion-interaction of aqueous solutions.