Abstract: The carbon reduction advantages of substitute clinker technology for cement industry are obvious. Calcined coal-series kaolin, as a high activity and low carbon material, can be used as a mixture to replace some clinker. In order to clarify the law of influence of fluidized calcination conditions on product activity and the activation mechanism of fluidized calcination, this paper carried out the calcination experiment of calcined coal-series kaolin with self-designed fluidized calcination equipment, and explored the law of influence of factors such as calcination temperature, calcination time and particle size of raw materials on product activity. The microstructure of calcined products was characterized by XRD and FTIR, and the activation mechanism of calcined coal-series kaolin was revealed. The results show that the optimum fluidization activation temperature of calcined coal-series kaolin is about 750 ℃, at which the concentration of Al³⁺ and Si⁴⁺ of calcined products is the highest, and the activity of volcanic ash is the best. Prolonging the holding time in a certain range is conducive to the activation of product activity. When the calcination time reaches 30min, the product activity increases by 78%, and further increasing the holding time has little effect on the activity. Fine particle size raw material has a positive effect on the activation of volcanic ash activity, but very fine raw material is not conducive to practical production and use. Through XRD and FTIR spectra of calcined products, it is found that the internal and external hydroxyl groups of kaolinite can be effectively removed by fluidized calcination, and its stable crystal structure is destroyed and transformed into subcrystalline metakaolinite, and Al^Ⅵ is transformed into Al^Ⅳ. From the relationship between calcined product activity and structure change, it can be seen that the activity source of calcined coal-series kaolin is the change of crystallinity and aluminum coordination form caused by dehydroxylation of kaolinite minerals.