Submerged steam jet condensation is widely applied in various fields because of its high heat transfer efficiency. In this paper, sonic steam jet condensation through a double-hole nozzle was numerically researched. First, the effect of L/D (pitch to diameter) on steam plumes was investigated. When L/D increased from 1.2 to 2.5, two steam plumes transformed from merging into one steam plume to being independent. Besides, thermal hydraulic parameters along radial directions were analyzed, revealing the existence of expansion and compression waves. Radial distributions of steam volume fraction, temperature and velocity were all largely symmetric about nozzle centerline and there all existed minimum values at nozzle centerline position. Finally, the effect of L/D on thermal hydraulic parameters of nozzle centerline was obtained. There existed peak values for steam volume fraction, temperature and velocity of nozzle centerline at one position. As L/D increased, the peak value decreased and its position moved downstream. (C) 2017 Published by Elsevier Ltd.