The phase equilibria of the ternary system NaCl-SrCl2-H2O at 273 and 308 K and quaternary system LiCl-NaCl-SrCl2-H2O at 308 K were measured by the isothermal dissolution equilibrium method. The phase diagrams of the ternary system at two temperatures both contain one invariant point, two univariant curves, and two crystallization fields (SrCl2 center dot 6H(2)O and NaCl). The phase equilibria of this ternary system were also compared and discussed at different temperatures. The phase diagram of the quaternary system LiCl-NaCl-SrCl2-H2O at 308 K consists of two invariant points, five univariant curves, and four crystallization fields (which are corresponding to SrCl2 center dot 6H(2)O, SrCl2 center dot 2H(2)O, LiCl center dot H2O, and NaCl). The Pitzer model known as an ion-interaction model has been successfully used to calculate the solubilities of salts in water salt systems with an experimental accuracy. Based on the Pitzer model parameters from the literatures, the Pitzer model was used to predict the solubilities of salts in the ternary system NaCl-SrCl2-H2O at 273 and 308 K. The comparisons show that the calculated results are in good agreement with those of experiment.