Abstract: The karst process is carbon sequestration for atmosphere CO₂. Karst carbon sequestration (KCS) value depends on the discharge of karst catchment and inorganic carbon concentration of water body. Based on the data from the mornitoring station on Banzhai subterranean stream located in Maolan National Nature Reserve of Guizhou, the influcent factors of KCS have been analyzed. It shows that the KCS is about 353 t C per year in the catchment of Banzhai subterranean stream, and there is good liner relationship between KCS and discharge at different time scales. Therefore, how to mornitor the discharge accurately is the key to KCS estimation. And the stations with real-time monitoring function are very important for KCS calculation because of strong seasonal variability of karst water cycle.