The paper conducts a quantitative study on the accumulative effect of the sedimentation and release of the sediment pollutants in the offshore area from Guanhe to Liezihe Estuary of Jiangsu along China coast. The study begins with the index of major pollutants in the sediment of this area and establishes the calculation relations of them between the water over the seabed and sediment pollutants. The sedimentation flux of suspended substances is calculated taking into account the mud-sand absorption in the river estuaries and the change of sediment release with time and space. Hydrodynamic force as the basic principle as well as the determining factor for offshore sediment release is analyzed in the last section of the paper. The model for the sedimentation release and the calculation formula for the sediment release ratio are established, and related parameters are set based on actual measurement and analysis of space attenuation of sediment release. Innovation is made for the “method of concentration difference location for sediment mixture” and the increment of pollutants and decrement of environmental capacity within a specific area are calculated. Calculation and verification are also carried out based on the data from actual measurement.