Direct Contact Condensation of steam jet through multi-nozzle is increasingly used in various industrial systems, such as the steam discharging condensation suppression pool. However, comparatively fewer investigations are reported on steam injection into subcooled water through multi-nozzle and the mechanism of steam condensation in the water tank is still unclear. This paper presents a numerical simulation method to reveal the physical mechanism of direct contact condensation of steam through an opposite nozzle. The Volume of Fluid multiphase flow model of FLUENT is used to accurately capture the two-phase interface. A thermal equilibrium model- the "two resistance model" is introduced to simulate the phenomenon of direct contact condensation of steam jet. Simulation results show that two typical condensation regimes were observed, which are Chugging, Condensation Oscillation. In particular, the water in the tank can be sucked into the nozzle periodically due to the rapid condensation of steam in Chugging regimes. The bubbles undergo three processes simultaneously in one nozzle instead of two nozzles, which are growth, necking and collapse. In addition, two typical pressure wave shapes of pulse oscillation and continuous oscillation are identified， which is consistent with previous experimental studies. The maximum pressure pulse peak is about 800 kPa measured in the nozzle and 40 kPa in the pool.