The solid liquid equilibria in the quinary system Na+, K+//Cl-, SO42-, B4O72--H2O at 323 K has been studied experimentally using the method of isothermal solution saturation. Solubilities and densities of the solution of the quinary system were measured. On the basis of the solubility data and corresponding equilibrium solids, the dry-salt phase diagram and water content diagram of the quinary system were plotted, respectively. In the dry-salt solubility diagram, there are four invariant points, nine univariant curves, and six fields of crystallization saturated with Na2B4O7 center dot 10H(2)O, where the solids are Na2SO4, Na2SO4 center dot 3K(2)SO(4)(Gla), K2SO4, K2B4O7 center dot 4H(2)O, NaCl, and KCl, respectively. The experimental results show that Na2SO4, Na2SO4 center dot 3K(2)SO(4)(Gla), K2SO4, and K2B4O7 center dot 4H(2)O have bigger fields of crystallization than other salts in the quinary system Na+, K+//Cl-, SO42-, B4O72--H2O at 323 K.