Based on data from highresolution singlechannel seismic surveys in 2009, former investigation data and neighboring terrestrial hydrogeological data at the Yangtze River delta of Shanghai, writers interpreted, analyzed and studied all seismic data synthetically. Distributing feature of submarine Quaternary sediment was found out. Locations of paleoriver channels of Yangtze River and Qiantang River during the early Pleistocene were probed primarily. The study has revealed that at north of Qiantang River mouth, west to survey area, north Shengsi archipelago and No.2 Shengsi well, and northeast sea area of Shengsi, the Quaternary stratum is very thick, the predicted distribution areas of paleoriver channel in early Pleistocene are possible abundant areas of marine freshwater resources. These data and conclusions may be helpful in further investigation of submarine freshwater resources and lay scientific basis on submarine freshwater sources exploitation at north Zhoushan sea area.