Abstract: Since 2019, the total volume of annual dredging in Changjiang Estuary is about 7 000×10⁴m³. After 7 existing dredging stations closed down, the capacity of the dumping volume in Changjiang Estuary is only about 3 000×10⁴m³, and the dredging material disposal gap is about 4 000×10⁴m³. Therefore, it is necessary to chose new marine dumping areas in time. The numerical model of FVCOM is used to simulate the diffusion of dumping silts in the candidate dumping area for the impacts. According to the statistic data from the Changjiang Estuary Waterway Administration, an actual capacity of 12 000 m³ is considered for the simulation of representative dredging vessel. The simulation results show that the suspended solids mainly diffuse in a spiral shape around the dumping area. As results, the 10 mg/L increment envelope of 4 candidate dumping areas will not significantly affect the nearby main waterway and the environmental sensitive areas in surroundings according to the diffusion range. Among them, the candidate dumping area D has the largest influence range and the next is C. The diffusions from A and B have smaller influencing ranges. Dynamically when two candidate dumping areas (A and B) on the north side of the deep waterway are dumped and diffused, the candidate of silting back to the south deep waterway is greater, and the hydrodynamic conditions in the south side of the deep waterway are better than those in the north side. According to the range influenced and dynamic conditions of mud diffusion after dumping, the candidate dumping site C is the best.