The global carbon cycle is an important factor for studying climate change. The adjustment of karstification to atmospheric CO₂ concentration and its close relationship with soil CO₂ are gaining more attention. The consumption of CO₂ by the karstification process can weaken the carbon source of the atmosphere, and the study of soil CO₂ is useful for clarifying the karst carbon cycle. Therefore, the effect of climate condition, soil property and land use type on soil CO₂ and the karst carbon cycle is examined. Furthermore, the effect of other acids such as HNO₃ and H₂SO₄ on the karst carbon cycle is also considered in this review. Because the factors all connect with one another, research on the karst carbon sink must consider every factor and should be conducted in accordance with earth system science and karst dynamic system theory.