Abstract: The knowledge of global carbon cycle is critical to understanding of today’s atmospheric CO₂ contents and varying of atmospheric CO₂ contents in the future. Conventional researches of global carbon cycle focus mainly on the carbon cycling among atmosphere, hydrosphere, and biosphere at Earth’s surface. Carbon reservoirs and carbon geochemical cycling within Earth’s interior had hardly studied in the past. At present  these conventional research methods have hardly illustrated the evolution of CO₂ contents of atmosphere. Deep carbon research, aiming at the carbon two-way exchanging between Earth’s interior and surface, became a current research hot-spot. Carbonatites are mainly made up of carbonate minerals and are the rocks of highest content of carbon within Earth’s interior. Therefore, carbonatites are the target of deep carbon cycling research. Current studies are further revealed that carbon from most carbonatites worldwide is from atmospheric CO₂, and thus, is recycling carbon. New formation of carbonate-bearing sedimentary rocks at surface, at the expense of huge atmospheric CO₂, were transferred into Earth’s interior through subduciton zones, which were experienced (ultra)high-temperature metamorphism under water conditions, and subsequently partial melting to form carbonate magmas within Earth’s interior. The new carbonate magmas moved upwards into upper crust, or even at surface, to form carbonatites. Carbon could go back to Earth’s surface. Therefore, the carbon cycling between Earth’s surface and interior was controlled by tectonic movements. Moreover, the long-term varying of atmospheric CO₂ contents is mainly driven by global tectonic activities.