Based on the vegetation inventory data, we investigated the density, storage and spatial characteristics and dynamics of vegetation carbon in Northwest Guangxi, China from 2005 to 2010, using biomass expansion factors and spatial analysis, respectively. The results showed that the total storage of vegetation carbon increased from 4.19 × 10⁴ t to 4.27 × 10⁴ t, about 1.84% per year. Similarly, the density of vegetation carbon also increased from 29.04t/hm² to 29.57 t/hm². Vegetation carbon density was highest (>40 t/hm²) in National Nature Reserve. From 2005 to 2010, vegetation carbon density in the previously non-vegetated land increased significantly through artificial seeding, direct seeding, aerial seeding or natural germination. Vegetation carbon density of revegetated land through Conversion of Cropland into Forestland Program was also increased by 3.00 t/hm². Vegetation carbon density from all types of forest stand was increased. With regards to the spatial distribution of carbon storage and density, the density was higher in the west, north, but lower in the middle-east, south. The average carbon density was more than 40 t/hm² in the west but lower than 25 t/hm² in the east and middle. The carbon storage and density in the karst areas and non-karst areas increased. Furthermore, vegetation carbon density in seven counties had increased to higher grade. Our study indicated that the carbon storage and density of vegetation in the study area was increased significantly and ecosystem conditions was improved through the application of policies of karst rocky desertification control, such as ecological migration and Conversion of Cropland into Forestland Program.