Abstract: The traditional core power PID controller is designed based on a local core model at a single power level. It is difficult to accurately describe the control of the whole core power level range. Therefore, based on five transfer function models at different power levels, the core fuzzy multi-model was established by weighting the triangular membership function. According to the model, the core power fuzzy PID control was designed. Taking TMI PWR core as the object of study, the control simulations of core power tracking and temperature disturbance at core inlet at different initial power levels were carried out. The results show that the core power fuzzy PID controller based on the fuzzy multi-model design can achieve good control of the core power.