Abstract: The lumped parameter model of heat transfer coupling with double group point reactor model was used to simulate reactivity disturbance for small pressurized water reactor at higher power condition and lower power condition, respectively. The results of simulation from this method were compared with those of calculation from three dimensions model. It is shown that this model is suitable to be used to simulate the peak and change trends of power and temperature when a reactivity disturbance is induced into a small pressurized water reactor, and it can be used to predict the danger of reactivity disturbance under normal and accident conditions for small pressurized water reactor because it costs shorter computation time and satisfies the ask of engineering precision.