Lake Poyang is the largest freshwater lake in China and one of the two remaining lakes freely connected with the Yangtze River in the middle reaches of the Yangtze River. Reconstruction of the spatiotemporal dynamics of the lake-wetland that are freely connected with the Yangtze River for the recent century is of great significance for Lake Poyang wetland restoration and protection and ecosystem services promotion. The present study used two periods of historic topographic maps and remote sensing products to reconstruct the Yangtze connected lake-wetland dynamics database covering the 1930s, 1970s, 1990s, 2000s and 2010s. Impacts of land use changes as well as hydrological connectivity changes on lake-wetland dynamics were explored. Results showed that Lake Poyang wetland area decreased from 5024.3 km² in the 1930s to 3232.7 km² in the 2010s, with a loss rate of 35.7%, of which most of the loss occurred between the 1930s and 1970s, with a loss rate of 33.2%. The lake-wetland loss is mainly distributed in the tail of Gan and Rao Rivers and the Kangshan polder. Moreover, a total of 1149.6 km² of lake-wetland has been converted into cultivated land due to reclamation since the 1930s, which is the main land use change type of lake-wetland. In addition, compared with the 1930s, a total of 683.4 km² lake-wetland was separated from the main lake, from which the hydrological rhythm was independent since then. The geostatistical hydrological connectivity curve of different historic periods also indicated that both the horizontal and longitudinal hydrological connectivity decreased for certain extent for the past century and remained relative stable since the 1990s. This study could provide reference states and data basis for the ecological restoration and ecosystem service promotion of Lake Poyang and even for the middle reaches of the Yangtze River.