Land cover change is an important factor affecting the climate system and has important research significance in global climate change researches. Gridded historical land use data have been widely used in various global change models. This study used the military topographic map of the Republic of China as the basic data source and modern administrative divisions as the base map, to reconstruct the spatial distribution of croplands in the Dongting Lake district of Hunan during the period of Republic of China. To compare with the HYDE 3.1 data, the cropland data were constructed at a spatial resolution of 10 km×10 km. Results show that: (1) the total area of croplands in Dongting Lake district during the period of Republic of China was about 11432.01 km ², accounting for 44% of the study area. The area of croplands in Hanshou, Huarong, Ding cheng, and Li xian, was the largest, dominated by dike farmland. Linli, Miluo, and Yueyang had less croplands, which were mainly non-dike cultivated land; (2) the land reclamation rate of Dongting Lake district during this period was large, with the maximum value greater than 90%. High reclamation areas with reclamation rate >40% accounted for 61%, and mainly occurred in the river estuary regions or alluvial plain. Low reclamation areas with <=40% accounted for 39%, and mainly distributed in the hilly landscape area; (3) compared to the HYDE 3.1 dataset, the error of constructed cropland area within a grid (10 km×10 km) greater than 40% accounted for 17%, which was mainly affected by the distribution of rivers. The reconstruction area in the HYDE 3.1 dataset was relatively large. It was difficult to consider the distribution of water systems in a small area, which leads to a relatively low reconstruction accuracy in the Dongting Lake district of Hunan. This paper uses the measured maps of the Republic of China to reconstruct the spatial distribution of croplands in the embankment area of the Dongting lake during this period, which provides basic data for land use and regional sustainable development in the lake area.