Abstract: In this paper, the CNP600 unit is taken as the case of study the influence of the reactor power upon the axial power deviation is analyzed through theoretical analysis and the Core Design program simulation calculation. The results show that for a balanced cycle, the relationship between the deviation of the reactor power and the axial power is close to the quadratic function, and the characteristics of the quadratic function are related to the core loading mode and core burn-up. The influence of the reactor power upon the axial power deviation is of great significance to the control of the reactor axial power deviation.