Wide collection is performed on the dating materials of buried paleo-trees, peat and shells, and also the cho-rography and historical document in the Yangtze Delta. All the ¹⁴C data are calibrated into calendar years. The sea level changes in the Yangtze Delta are reconstructed from the ¹⁴C-dated shell ridges and peat. The research results indicate that frequently occurring flood periods matched the climatically warm and wet periods well. 6 flooding periods correspond to the 6 periods characterized by relatively warm and humid. Humid and warm climate is in close relation to the occurrence of floods. Additionally, the Yangtze Delta is geomorphologically low-lying, making flood events occurred to the region susceptive to sea-level changes other than the main flood-inducing factors like excessive precipitation and human activities. In the middle and lower reaches of the Yangtze River, the rise of sea level plays a key role in the deposition of the sand on the riverbed. With the rise of the sea level and the rive bed, the water level of the middle and lower part of the Yangtze River rises correspondingly, the result of which is to make the discharge of excessive water difficult during the flood period, intensifying the loss induced from flood disasters. The pushing to the water flow of the Yangtze Hiver from the high sea level is also one of the factors intensifying the negative effect of the flood disaster. Digital modeling results indicate that rising of sea level is the main driving factor for the deposition of the riverbed sand after the Ice Age. The result of this deposition is the decreasing of the transportation capacity of the flood discharge, together with the rising of the sea level; all these factors make the transportation of the flood discharge more difficult. This paper put under consideration the influence the sea-level changes on the flood events occurred to the Yangtze Delta, the research results are theoretically and practically meaningful in forecasting the occurrence of flood disasters and strengthening the prevention of coastal disasters.