Abstract: To alleviate heat transfer tube rupture accident of steam generator and study power uprating of nuclear power plant, referring operating parameters of Daya Bay Nuclear Power Plant steam generator, the one-dimensional mathematical model of nuclear steam generator was established based on distributed parameter method. The dynamic simulation program was developed based on MATLAB, and the steam generator thermal parameter simulation calculation was conducted when operating conditions change. The calculation results show that when the secondary side operating temperature decreases or the secondary side flow increases, the secondary side preheating section becomes shorter and the outlet enthalpy rises sharply. The mass fraction increases 54% and 28% respectively while temperature decreases and flow increases compared with full power normal operating conditions. The temperatures of the primary side, secondary side and wall of U-tube decrease. The temperature drops of the primary coolant and the inner wall increase. The calculation results which reveal the inherent heat transfer rules of steam generator can support relevant operation, such as U-tube degradation alleviation and power uprating.