Hydrographic microstructure measurements were carried out in the northern East China Sea in August 2005 and August 2006. The velocity data measured from moored ADCPs and time series of temperature obtained from moored thermistor chains reveal a couple of sharp variations corresponding to the solitary internal wave. Internal waves are generally lasted approximately 3 hours during the phase of low tide in the mooring sites. The existence of internal solitary waves is consistent with the observations from Synthetic Aperture Radar images in the Yellow and East China Seas close to the observation area. During internal wave episodes, high-frequency fluctuations of all components of the velocity occur for almost entire water column, suggesting vertical transport of salinity to the surface low salinity water (i.e., the Changjiang Diluted Water) from the high salinity water below the halocline.