Abstract: Because of its strong condensation heat transfer capability, steam jet condensation process is widely used in advanced passive reactor safety system, but it will produce strong pressure oscillation. In order to understand the essence of condensation oscillation of steam immersed jet, the key calculation models such as mass exchange model of bubble boundary layer, bubble control equation model, calculation model of steam pressure in bubble and pressure calculation model at any position in water tank were established based on the basic conservation equation, and the thermal hydraulic model to simulate the process of steam bubble condensation oscillation in water tank was constructed. The simulation value with time variation was calculated by using the calculation formula of bubble radius and pressure in the pool given by the model, and the calculation results were compared with the experimental data of Chun experiment and Fukuda experiment. The validity of the model was verified, which lays a theoretical foundation for further research on condensation oscillation mechanism.