Abstract: On the basis of some hydrological data obtained from observation at the upper and middle section of the north passage during the spring tide in the flood and dry seasons from 2006 to 2013, and using the methods of statistics data, harmonic analysis and tidal range’s proportion conversion，analyses of variation characteristics of tidal current and suspended sediment concentration (SSC) before and after construction of the third stage of the Yangtze River estuary deepwater channel regulation works have been made in this paper. The analysis results show that：①the amplitudes of M4 and SM4 tide are strengthened due to the construction of the regulation works in the upper and middle section of the north passage; and the average tidal range decreases in the middle section of the north passage；②after the completion of the regulation works, the deep-average major axis of M2 increases during the flood seasons, while decreases during the dry seasons, and the direction of the major axis in both seasons turns to the north, and the ellipticity decreases. The flood and ebb tide average tidal current velocity decreases no matter whether in the flood or dry seasons, and the preferential flow also decreases; ③in the middle section of the north passage, the most contribution to SSC is residual current, and then is M4, the third one is M2. After the construction of the regulation works, the flow and ebb tide average tidal current velocity decreases, and preferential sand also decreases; ④in the upper and middle section of the north passage, the non-linear characteristics of tide dynamics tend to be strengthened, which is mainly affected by its narrowed deepening works. Heightening the south dike becomes a main factor in reducing the flow velocity along the middle section. The difference between the flood and dry seasons of the preferential flow and preferential sand is mainly affected by the upper incoming flow and the suspended sediment. Sediment resuspension is a major source of the suspended sediment in the middle section of the north passage, and the differences between the flood and dry seasons of the suspended sediment concentration are controlled respectively by the upper incoming flow and the suspended sediment as well as the tidal current dynamic strength.