With a subtropical climate, Guangxi has a typical karst landscape. Land degradation has become a serious environmental issue due to its high vulnerability caused by the joint effect of natural settings in geology, topography, rainfall, and vegetative cover, as well as human activities such as deforestation. Its eco-environment has deteriorated over recent years while cultivated land is disappearing quickly. This, in turn, has exacerbated the poverty level in rural areas. In this study we monitored the spatial distribution of land degradation and its temporal evolution using Landsat TM/ETM images of the late 1980s, mid-1990s and late 2000 (for simplicity, we identified them as 1985, 1995 and 2000). We also explored the causes of its initiation and expansion. Through constructing regression models using all the relevant variables and considering the lagged effects as well as fixed effects, we quantified the exact role of different factors in causing land degradation in the study area with new findings. Based on these results we further analyzed the hazard of land degradation and proposed a few practical rehabilitation measures, including forestation, infrastructure projects, and ecological projects. The findings in this study are invaluable in preserving, restoring, and reconstructing the degraded environment in Guangxi and other karst areas in Southwest China while alleviating poverty in rural areas.