In view of the characteristic of the deep underground brine that is rich in sodium, potassium, magnesium, calcium, strontium, chlorine, and bromide in the Sichuan basin, solid-liquid equilibria in quinary system NaBr-KBr-MgBr2-SrBr2-H2O were accurately determined at 323 K by the method of isothermal dissolution equilibrium. According to the experimental data, the three-dimensional equilibrium phase diagram was obtained. It consists of ten univariant curves, three invariant points, and six crystallization regions. The solids in crystallization regions correspond to NaBr center dot 2H(2)O, NaBr, SrBr2 center dot 6H(2)O, MgBr2 center dot 6H(2)O, KBr, and KBr center dot MgBr2 center dot 6H(2)O, of which MgBr2 center dot 6H(2)O has the minimum crystallization region and KBr has the largest crystallization region, which is bigger than half of the phase diagram. In addition, two-dimensional projections of the saturation surfaces of KBr, SrBr2 center dot 6H(2)O, and MgBr2 center dot 6H(2)O were also analyzed.