The lake- wetland ecological system is sensitive to climate change and human activities. This study investigated the ecological changes of Wuchang Lake wetland (located at the downstream of the Yangtze River) from 1980 to 2010, and the potential causes of wetland degradation. We first overviewed the landscape changes in the study area by analyzing the Landsat MSS/TM imageries; and then examined the dynamics of hydrometeorology during the study period. Based on the analysis of changes of landscape patterns and variations of hydrometeorological variables, the natural and anthropogenic causes of Wuchang Lake wetland ecosystem degradation were discussed and differentiated. Results show that over the past three decades the total area of Wuchang Lake has decreased by 40%. In particular, area of the Qingcao Lake at the downstream of the lake- wetland system has over 73%, from 52.76 km~2 to 13.92 km~2. The area of construction land, which manifests the human activity in the watershed, had increased significantly since the building of the Anjiu Road across the lake. The average annual temperature in the study area showed a significant increasing trend, while the annual rainfall and evapotranspiration were relatively stable with little variations. We concluded that the degradation of the Wuchang Lake wetland was accelerated mainly by constructions in the area and the increased temperature, while the annual rainfall and evapotranspiration had little influence.