In this paper, the authors validate whether the position of 137 Cs maximum represents the year 1963 in this area by establishing a model. In this model, the authors used annual 137 Cs deposition at Tokyo and precipitation of Tokyo and Shanghai to carry out the annual 137 Cs deposition in Yangtze River Estuary,and then,the authors calculated the maximum activity in the 137 Cs profile in the sediment which depended on the deposition rate and the sub-sampling interval. By comparing the 137 Cs maximum in the 17 profiles (11 profiles in this work, and 6 from published data in the subaqueous delta of Yangtze River Estuary) with the calculated values, 9 cores gave the results, which showed that the maximum of 137 Cs calculated from the model consistent with that from the measured date.