本文根据地学原理，建立了长江口泥沙的来源分析与数量计算的模式。定量分析了长江口泥沙来源，计算了泥沙的数量。通过验证表明沙量的计算值与验证值两者十分吻合。

According to the regional geologic and physiographic characteristics and their effect on minerals composition of sediment, the sources of the sediment at: the Yangtze River Estuary can be divided into 3 supplying regions, namely, the Yangtze River upstream of Jiangyin (x₁), the abandoned Yellow River Delta at the north of Jiangsu Province (x₂) and the Hangzhou Bay (x₃). The converging region is the Yangtze River Estuary (y). Sampling sites have been set up at the supplying regions and in the converging region. Based on evaluations of heavy minerals and clay minerals, the author holds that mineralogical characters of sediment of the Yangtze River Estuary are governed by the geologic and physiographic conditions of the supplying regions. According to the principle of equilibrium of sediment load, equations of the heavy mineral or the clay mineral classification are presented. By means of least square method, a normal equation for calculating the converging percentages from all the supplying regions is give below: [aa]x₁+[ab]x₂+…+[at]x_m=[ay] [ab]x₁+[bb]x₂+…+[bt]x_m=[by] [at]x₁+[bt]x₂+…+[tt]x_n=[ty] Where ,they are the coeffcients related to heavy minerals or clay minerals, By which the converging percentage of each of the supplying regions is calculated. The result of calculation shows that over 92.1% of silt and fine sand, 94.6% of clay sediment, come from the Yangtze River. The research shows that most sediments are deposited in the Yangtze River Estuary, the remainder to be transported to the southeast. As the converging percentage of the Yangtze River upstream (x₁) is known and the total amount of sediment supply from Datong Station is also known (475.00 million tons per year), the amount of sediment at the Yangtze River Estuary is computed, which is 460.50 million tons per year. This numerical value agrees quite well with the value of 460.10 million tons per year by comparing with the topographic map of the Yangtze River Estuary in 1915 and in 1963.