When steam with high velocity is injected into quiescent subcooled water through a sonic nozzle, the phenomenon that the total pressure along central axis at the tail of steam plume can be larger than the total pressure of steam inlet was observed in some experiments, but the reason is not clear till now because of the restriction of experimental method. It is very hard to obtain the static pressure, the velocity of water and steam, as well as the dynamic pressure of steam and water. To reveal the reason, three-dimensional steady simulation was carried out to study stable steam jet in subcooled water. A thermal equilibrium phase change model was inserted into Fluent as a user defined function (UDF) to model the DCC process. After the simulation model being validated, the effect of steam mass flux and water temperature on the shape of steam plume was studied, and the thermal hydraulic behavior along axial direction was investigated. Then the phenomenon that the total pressure at the tail of steam plume can be larger than that of steam inlet was also observed in the simulation result. It was found that the axial locations where the total pressure and the dynamic pressure of water reached the peak were the same, and the locations were all located at the tail of steam plume. The inference that the dynamic pressure of water resulted in the total pressure at the tail of steam plume larger than that of steam inlet was made. The inference was still valid under different steam pressures and water temperatures. Then the reason why the dynamic pressure of water was the largest at the tail of steam plume was also investigated. (C) 2016 Elsevier Ltd. All rights reserved.