Taking the large-scale engineering group in the Yangtze River Estuary as the research object，we apply the CJK3D-WEM two-dimensional tidal current mathematical model to study the influence and cumulative effect of engineering group on the hydrodynamic pattern.The results show that after the implementation of large-scale engineering group such as the north passage deepwater channel regulation project，the diversion project of the north and south channel in the Yangtze River Estuary，siltation promoting circle of Nanhui beach and Hengsha east beach from 1998 to 2016，the flood tide volume，tidal range，the maximum velocity in high tide and ebb tide of Xuliujing reach have been reduced by about 10%，6%，9% and 4% respectively，and the diversion ratio of the north passage has been reduced from 60% to about 40%.The gradual implementation of the engineering group has obvious cumulative effect on the hydrodynamic changes of the upper reaches.Among many projects，the north passage deepwater channel regulation project has the greatest impact on the upper reaches，accounting for about 50%，where the first phase of the project accounts for a large proportion.The Nanhui beach encircling project has a greater impact on the upstream，and the Hengsha east beach siltation promoting and encircling project has the least impact.