Analysis and investigation on water dynamic characteristics at the water surface to bottom under spring, middle and neap tides were made based on synchronously observed data for nearly 40km distance from Zhuying upstream to estuary during Dec.10-25, 2009. The results show that the velocities in Modaomen waterway are not speed with only average 0.5m/s and 0.76m/s on water surface respectively during rising and ebb duration in spring. Water dynamic characteristics commonly appear that the velocities during ebbing time are more than that during rising on water surface but there is little difference on bottom. Rising and ebbing velocities increase from neap to spring tides. Tidal rising duration is less than ebb on water surface in the waterway with converse feature on bottom. There is converse flowing phenomena along water depth between water surface and bottom in the Modaomen estuary and waterway during the second ebb duration after the first long time ebbing with revolving location closer to water surface.