The rational utilization of groundwater resources is the key to achieving the carbon peaking and carbon neutrality goals, strengthening the comprehensive control of karst rock desertification and soil erosion in the ecological environment. On the southern wing of Tongmaling anticline in southeast Chongqing, Longtan trough valley--a part of Wuling Mountain area--is located in Youyang county, Chongqing City, China. The karst development is strong in the trough valley area, and the distribution of groundwater is extensive. At the same time, the problem of rocky desertification is severe in this area, so the efficient utilization of water resources and ecological restoration are especially important. The objective of this study is to explore the flow characteristics of karst spring and structure types of aquifer medium, and to further analyze the variation characteristics of inorganic carbon flux in the ecological restoration area of rock desertification control. In this study, the flow attenuation equation and hydrochemical runoff method are used to estimate and analyze attenuation process and inorganic carbon flux of Laoquan spring based on the re-vegetation in a karst rocky desertification area in Longtan trough valley in Youyang county, Chongqing City, Southwest China. The results show that: (1) The flow attenuation process of Laoquan spring is divided into two sub-dynamics with attenuation coefficients of 0.0892 and 0.0196, respectively. The attenuation process of this spring mainly occurs on the first sub-dynamics. In the aquifer medium of groundwater system, the ratio of pipeline to fissure is significant. The strong water conduction effect of aquifer medium leads to the weak capacity of Laoquan spring to regulate and store rainfall infiltration water. (2) The variation process of the carbon flux of Laoquan spring during the rainstorm period is divided into four stages, and the carbon flux has obvious variation characteristics with the flow. The carbon flux during the rainstorm period is 97.64 kg⋅km-2⋅d-1. In the summer drought period (from the end of July to the end of August), the carbon flux of Laoquan spring has obvious diurnal variation characteristics, low at night and high in the day. The soil CO2 concentration, water CO2 concentration and carbon flux of Laoquan spring are synchronized in the diurnal variation, and the carbon flux in the summer drought period is 18.23 kg⋅km-2⋅d-1. (3) The climate instability can affect the carbon flux of Laoquan spring. The precipitation of this spring in summer is positively correlated with the carbon flux (R=0.78), and the evaporation is negatively correlated with the carbon flux (R=-0.36). The change of land use mode has a significant effect on the carbon flux of Laoquan spring. The correlation coefficient between HCO3-1 concentration and soil CO2 concentration based on the monthly mean value of Laoquan spring is 0.64, indicating that HCO3-1 in Laoquan spring sensitively responds to the change of soil CO2. The correlation coefficient between the annual spring carbon flux and the annual soil CO2 concentration is 0.90, and the average annual δ13CDIC shows an obvious negative trend, indicating that land use change (Vegetation Restoration) is conducive to the increasing of soil CO2 concentration and carbon flux. (4) From 2018 to 2021, the carbon flux in Laoquan spring was 11.66, 10.33, 21.31 and 16.9 t⋅km-2⋅a-1, respectively, showing an increasing trend with fluctuation. The annual inorganic carbon flux is 15.05 t⋅km-2⋅a-1 (CO2). The carbon sink capacity should be enhanced by the improvement of comprehensive control measures of rocky desertification. Therefore, in the process of rocky desertification control, it is necessary to make scientific use of karst water resources and heighten the awareness of karst environment protection, especially the scientific use and management of water resources in summer rainstorm and summer drought. In addition, it is necessary to boost regional carbon sink capacity by restoring natural dominant vegetation in rocky desertification control areas. [ABSTRACT FROM AUTHOR]