||Three-dimensional steady method was employed to simulate the process of stable supersonic steam jet condensed into a water pool. A thermal equilibrium phase change model was inserted into Ansys as a user defined function to simulate the condensation process. To testify the correctness of simulation model, steam plume and radial temperature distribution were compared between experiment and simulation. Then four kinds of steam plume shapes, including contraction, expansion-contraction, double-expansion-contraction, and contraction-expansion-contraction shapes, were observed from numerical results as experimental results indicated. Combined with the corresponding contours of steam void fraction, the distribution of axial thermodynamic parameters, such as pressure, temperature and velocity were analyzed for each kind of steam plume. The theory of expansion and compression wave was employed to explain the flow mechanism in each kind of steam plume.