Abstract: In order to study the characteristics of saltwater intrusion into the Yangtze (Changjiang) estuary and the saltwater spilling over from the north branch of the Yangtze estuary in dry seasons， two tidal synchronous hydrologic surveys were carried out in the bifurcation of the north branch and the south branch in December 2013 and February 2014. Analyses of the data have given several conclusions. Under the impacts of geomorphology, the salinity in the entrance of the north branch is an order of magnitude higher than that of water in the Baimao shoal. The salinity of water is negatively correlated to the runoff volume, while tidal range is positively related. The saltwater will spill over from the north branch while the runoff volume is relatively small and the tidal range is relatively large. Due to the backwater effects of the runoff, the spilling saltwater is forced to head for the north, so the salinity of the north channel of Baimao shoal is larger than that of the south channel. The wind stress has a significant effect on the salinity intrusion and the continuous south wind can decrease the intensity of the salinity intrusion in the north branch. The saltwater spilling over from the north branch flows on the south side of Baimao shoals north channel, and stays in Baimao shoal for several days during spring tide and the salinity in water around Baimao shoal reaches a maximum value in the moderate tide after the spring tidal.