Abstract: Ecologic footprint is an effective way to measure regional ecologic capacity and sustainability. Taking the representative karst ecologic vulnerable region, Pingguo county, as an example, the regional ecological footprint and ecologic capacity are calculated by means of the statistic data in 1990, 1995, 2000 and 2002. And then, on the basis of the results, the sustainability of regional ecosystem is analyzed. The results show that, from 1990 to 2002, the regional ecologic footprint increased continuously from 0. 8004 hkm^2/per cap to 1. 4444 hkm^2/per cap. The ecological capacity also increased by 26.83% from 1990 to 2002, but the value was very small in comparison to the average level in both Guangxi and China during the corresponding period. On the contrary, the ecologic capacity of arable area and pasture represent a decrease trend. Except forest and garden land, ecologic deficit has occurred in arable area, pasture and water area. Overall, the regional ecologic balance between ecologic capacity and ecologic footprint show increasing ecologic deficit, which indicates that the regional development is unsustainable.