The phases variation law of kaolinite-CaO-mineralizer (CaCl2,CaF2. CaSO4) system in the course of hydrothermal pretreating and calcining of pretreated products is investigated. Also,the gelatinization capacity and composition of calcined products and the relationship between the kind of mineralizer and the temperature of calcining are studied. It is concluded that both adjusting a suitable chemical composition and opting for composite rnineralizer can effectively inhibit the formation of inactive mineral C,AS improve the gelatinization capacity of calcined products. The phases variation law of kaolinite-CaO-mineralizer (CaCl2, CaF2. CaSO4) system in the course of hydrothermal pretreating and calcining of pretreated products is investigated. Also, the gelatinization capacity and composition of calcined products and the relationship between the kind of mineralizer and the temperature of calcining are studied. It is that that both prepare a suitable chemical composition and opting for composite rnineralizer can inhibit the formation of inactive mineral C, AS improve the gelatinization capacity of calcined products.