The effect of temperature rising inhibitor (TRI) on early hydration process of cement-fly ash-slag composite cementitious material was studied. By changing mass proportion of mineral additives in gel materials and amount of TRI, the hydration characteristics of cementitious materials were measured. The reaction rate constant, geometric crystal growth index and other dynamic parameters were calculated based on the Krstulovic-Dabic model. The results show that mineral additives and TRI delay the time of hydration and reduce the maximum hydration rate of cementitious materials. The hydration process of composite cementitious material can involve three stages, i.e. nucleation and crystal growth, interactions at phase boundaries and diffusion. The hydration process can be predicted by Krstulovic-Dabic model well. Mineral additives and TRI affect the crystallization of nucleation and crystal growth, and reduce the hydration rate of composite cementitious material at every stage.