Abstract: The characteristic of steam plume of sonic submerged jet in quiescent subcooled water was investigated experimentally with the inner diameter of 10 mm for the jet while the steam pressure was in the range of 0.2-0.8 MPa and the water temperature was in the range of 20-60 ℃. The results show that the dimensionless penetration length of steam plume increases with steam mass velocity and water temperature. Furthermore, the correlations were set up to predict the dimensionless penetration length and heat transfer coefficient. The predicted relative error of length of steam plume is within the band of ±15%, and the predicted relative error of heat transfer coefficient is within the band of ±12% in the shape of elliptic steam plume.