The domestic and foreign evaluations of ecosystem service value are difficult to draw on results accepted by the public and academia. This reflects the research methods are still not mature, need to continue to be improved. In this paper, an attempt has been made to give urban unit value of ecosystem services and set up the values per unit area in southwestern Guizhou of China, in accordance with unit value of global ecosystem services developed by Costanza, et al., Chinese one by Xie, et al. and the actual situation of karst region. The analysis revealed that in the study area, the total ecosystem service value is $1.876×109 in 2006, equivalent to 104.3% of 2006 GDP (Gross Domestic Product), $1.799×109（1US$=7.8136，2006）. If the rocks change into forest in the study area, ecosystem service value will add $0.221×109, equivalent to 12.28% of GDP in 2006. Therefore, we conclude that the ecosystem services value is higher, compared to the local economy. In addition, the rocky desertification area is larger, and has already seriously influenced ecosystem service function. The tasks of ecological environment protection, propaganda and education in this region are of great significance.