With the implementation of ecological restoration, the net area of rocky desertification has been reduced and vegetation coverage significantly improved in karst areas, southwest China. It is crucial to explore the trends in vegetation change and distinguish the driving forces under different karst terrain conditions. Based on the long-term time-series of GIMMS NDVI 3g images, the present study aimed to identify the vegetation changes at different spatial and temporal scales and non-stationary relationships between vegetation changes and driving forces in karst regions of Yunnan, Guangxi, and Guizhou Provinces with a combination of spatial autocorrelation, principal component analysis (PCA), and geographically weighted regression. The results showed that from 2001 to 2011 the growing season normalized difference vegetation index (GSN) significantly increased compared to that from 1982 to 2000 in the three regions. The GSN appeared spatially assembled (the Moran's index I_g was 0.90), while the extent of increase was significantly diverse for different areas (the variable coefficient was 43%). The PCA indicated that the main driving forces of vegetation change were climatic factors, soil texture, human activities, water availability, soil nutrients, and the level of social and economic conditions. The extent of impacts of the driving forces on vegetation change varied with different geographic positions. In addition, the main driving forces were spatially different under different karst landforms. Our study indicated that the differences of vegetation driving forces should be taken into consideration during future implementation of ecological restoration under different karst landforms.