Abstract: Taking the Moroccan desalination projects（NHR-10） developed by Tsinghua University as the prototype, the small integrated natural circulation nuclear heating reactor model was established. By the study of the load tracking transient condition and reactivity accident, the pressurizer characteristics and stability of the performance of nuclear heating reactor were analyzed.The results indicate that the subcooling of outlet in integrated nuclear heating reactor is small enough to ensure that boiling does not occur during the transient process of reactor, which is good to PWR. The upper gas space volume has effect on the pressure trends of the reactor during the transient process. Initial subcooling of outlet has little effect on the transient process and final result.Integrated nuclear heating reactor has good stability in PWR run mode.