Abstract: Tiandong County, a region typical of depressions among Karst peaks in Guangxi was selected as the research area. Based on GIS and RS technologies and the observation data of the meteorological stations, spatial distribution of ecological water demand in the study area was plotted and simulated by ArcGIS using the Penman-Monteith method as recommended by the Food and Agriculture Organization of the United Nations (FAO). Landscape pattern indices were extracted from the land use data obtained through interpretation of the Landsat 8 data for analysis of relationship between ecological water demand and landscape pattern. Results show that the annual quota of ecological water demand of the vegetation in Tiandong County varied between 85.91 and 339.27 mm, and it also did spatially, being high in the northern and southern mountainous areas and relatively low in the central, western and southeastern regions. Ecological water demand of vegetation was found to be significantly and negatively related to landscape diversity and fragmentation, with correlation coefficient being -0.198 and -0.186, respectively, while it was significantly and positively to landscape connectivity, with correlation coefficient being 0.221. All the findings in this study may serve as certain basis for optimization and management of regional landscape patterns and allocation of water resources.