Abstract: The goal of the karst critical zone research is to reveal the dynamic balance and evolution mechanism of the karst ecosystem, which can provide the sustainable management strategies of resources environment service for economic society. The research can indicate how to strengthen the flexibility of the karst critical zone under the reasonable Human activities, and provide the effective means to repair the damaged parts. Carbonate, as the soluble rock, gives the karst critical zone some particularities in structure and lithosphere-biosphere interaction of material cycling processes. Taking the karst area of Southwest China as an example, through summarizing the research results of many scholars, the authors revealed the regional difference of the karst critical zone development thickness, that explains why the thickness is several meters in Guilin karst area and one thousand meters in Wulong karst area of Chongqing. The vertical material cycling processes of the karst critical zone regard soil-surface karst zone as the central link, but it horizontally shows the island-like embedded distribution. The surface ecology is fragile. The carbon cycling processes of the karst critical zone include karst carbon cycling and ecology carbon cycling. The carbon sinks are composed of plant carbon sinks, soil carbon sinks and karst carbon sinks, and the total flux of these carbon sinks is 64.36 t/(km²·a) by the preliminary estimation.