Abstract: Based on the control requirements of the reactor cold start-up process with nuclear heating, the automatic pressure control of reactor cold start-up with nuclear heating is studied in this paper, and the method for the system pressure automatic control  in the process of cold start-up with nuclear heating are studied, and the automatic control method is designed and the control simulation verification is completed. At the same time, the problem of overpressure in cold start-up with water compaction state is simulated and analyzed. The interlock control methods to prevent overpressure accidents are proposed. The results show that, when the reactor power does not exceed a certain power level, the automatic pressure control method can realize the effective control of the reactor pressure during the cold start-up with nuclear heating.