Lake Dongting is the second largest freshwater lake in China, directly connected to the Yangtze River. It has significance of practical effects on flood control, drought prevention and wetland conservation. This study addresses spatial-temporal variation in water surface area of Lake Dongting and its relationship with water level at Chenglingji of the Yangtze River. Water surface area were extracted from multi-temporal images of the Terra/MODIS (moderate-resolution imaging spectroradiometer) for the years 2000-2012. In combination of water level data of Chenglingji, a loop-like relationship was explored between the lake water surface area and the water level. Our results show that the lake area decreased from 2000 to 2012, with a strong seasonal variation in terms of rising (April-June), flooding (July-September), retreating (October-December) and drying (January-March) periods. The inundated area displays a seasonal change of spatial pattern with expansion from lake center to its maximum bounds during February-August and contraction from its maximum bounds to lake center during September-January. The lake water surface has a good correlation with the water level at Chenglingji and the correlation coefficient varies in seasons with the minimum value for drying period, the maximum for flooding period, and relatively high values for rising and retreating periods. The variation is probably related to the difference in controlling factors in different time periods. The Yangtze River has a relatively large impact on the loop-like relationship in drying season and flooding season, especially for the east Lake Dongting, which is the case even for high-and low-water years. Our findings offer an insight into the complexity of river-lake relationship and provide an important basis for flooding prevention in Lake Dongting and the mid-and lower-reaches of Yangtze River.