Abstract: The goals of this paper are to establish the kinetic model of hydrothermal deactivation and the model of unit balance activity for FCC catalyst. At first, considering catalytic cracking reaction as a second-order reaction, the catalyst activity relating to hydrothermal deactivation is expressed as the ratio of cracking reaction rate for hydrothermal aged catalyst to cracking reaction rate for new catalyst. The kinetic model equations of hydrothermal deactivation for self-resistance are determined by considering that the catalyst hydrothermal deactivating is accompanied with the catalyst ultra-stabilization. Then, the hydrothermal deactivation kinetic models for self-resistance are developed through parameter estimations based on the steam aging experimental data of FCC catalyst. The results of statistics analysis show that first order deactivation kinetic model with second order self-resistance factor has higher precision. In other way, based on the flow property of complete stirred-tank reactor, the model of FCCU balance activity is developed. The study points out that the observed data of micro-reaction activity for FCCU balance catalyst is conformable with the calculated data with the model of unit balance activity. The prediction results of the balance activity model show that the micro-reaction activity of the FCCU balance catalyst increases quickly firstly, then increases slowly along with catalyst consumption. In the end, higher the regenerator temperature is or larger the catalyst content of regenerator is, the lower the micro-reaction activity of FCCU balance catalyst is.