Abstract: Carbonates are the biggest carbon reservoir in the world, karst carbon cycle composed of carbonates, water, CO₂, soil and microorganisms takes part in the global carbon cycle actively. Carbonate-weathering-related carbon sink is the main part of residual land sink. Water and CO₂ are the main drivers of carbonate-weathering, carbonate-weathering is the main diver of karst carbon cycle and regulates the concentration of CO₂in the atmosphere in geological time scale, which has the obvious carbon sink effection and is an important role in the carbon sink system.