Evaluating the coupling effects of climate variability and ecological restoration on carbonate rock weathering-related carbon sink (CS) is an important objective in current research on carbon cycle and climate change in karst ecosystems. In this study, we estimated the flux of CS (CSF) in the typical karst valley of Southwest China from 1992 to 2017 based on the thermodynamic dissolution model for carbonate rock. We extended our research by using the Lindeman-Merenda-Gold model to quantify the relative contribution rates of climate change and ecological restoration factors to CSF. We obtained the following results:1) annual average temperature and precipitation of the valley were both increasing continuously at rates of 0.06℃ per year and 12 mm per year, respectively, and after 2000, these rates of increase slowed down. The annual evapotranspiration increased before 2000, and decreased after that. 2) The increase rate of fractional vegetation cover (FVC) in the valley was 0.004 per year, and the proportion of increased area reached 95.07%, which indicated significant ecological restoration in the valley. 3) The annual average CSF in the valley was 9.42 t C km^-2 a^-1 with an increasing trend during the study period showing an average increase rate of 0.2 t C km^-2 a^-1, and the proportion of the area with increased CSF was 89.28%. 4) CSF in the valley was affected by climatic factors (precipitation, evapotranspiration, temperature) and ecological restoration factors (FVC); among these factors, precipitation, temperature, and FVC had a positive impact on CSF, whereas, evapotranspiration exerted a negative impact on CSF. The relative contribution rate of precipitation in the valley was the maximum among that of all factors, with a magnitude of 70.36%. 5) We revealed the coupling influence mechanism of climate change and ecological restoration on rock weathering process.