Abstract: In this paper, an identification modeling method was put forward. It combines the mechanism modeling and the parameter identification of autoregressive exogenous model based on least square method. The dynamic characteristics of nuclear power were identified with this method. The nuclear power dynamic characteristic model with the external reactive change as the input and the nuclear power variation as the output was established. The established model was verified in Matlab/Simulink. The feasibility of the identification method used for modeling of nuclear power dynamic characteristics and the availability of the established model were verified.