The hydrate phase assemblage and content evolutions of ye’elimite-anhydrite-limestone ternary system were studied based on the thermodynamic modelling. The results show that the evolutions of hydrate phase and pH value can be divided into 5 regions (region Ⅰ~Ⅴ) according to the content of anhydrite and limestone, and the change of pH value of the liquid phase in ye’elimite-anhydrite-limestone ternary system. The boundaries between region Ⅱ and region Ⅲ, Ⅳ are exactly the fully-reaction boundary of limestone. The boundary between region Ⅳ and region Ⅴ is exactly the fully-reaction boundary of anhydrite. The hydration model of ye’elimite-anhydrite-limestone ternary system is established based on the thermodynamic modelling and verified by experimental data. The research results provide an important theoretical basis for the study of the hydration mechanism of ye’elimite-anhydrite-limestone ternary system and the batching design of sulfoaluminate cement.