In this paper, we demonstrate the characteris-tics of strong internal solitons at the southern edge of Dong-sha Islands in the northern South China Sea (SCS) during ductivity temperature depth (CTD), acoustic Doppler current profiler (ADCP) and thermistor chain. Our measurements indicated that the strongest internal solitons were larger than 90 m in wave amplitude, and propagated approximately westward in traveling direction, with the maximum current strongest internal solitons occurred noticeably during May the diurnal-dominated spring internal tides.