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Abstract:The paper studies CO2degassing and controlling factors under the condition of contact metamorphism in the Shuangshan area, southern Tan‐Lu fault belt and the method of calculating the amount of CO2degassing. The results show that the amount of CO2degassing is controlled by the characteristics of the country rocks, including the thermal conductivity, penetrability, porosity and connectivity. Compositions, size and depth of intrusive rock also have an important influence on CO2degassing, i.e., they generated numerous cracks in the country rocks, and thus allowed the easy flow and accumulation of fluids. The amount of CO2flux in contact metamorphism is calculated quantitatively based on the metamorphic reaction and time‐integrated fluid flux. The value (0.729‐2.446×104mol/cm2) of CO2flux suggests that CO2was provided mainly by the contact metamorphic reaction. The generation and releasing of CO2are positively correlated with the degree of metamorphism, and XCO2in fluids gradually increases from dolomite zone to calcite zone, but in the zone of grossular, fluid flux is the largest and XCO2sharply decreases due to involvement of magmatic water. This study presents evidence that a large amount of industrial‐scale CO2can be produced during contact metamorphism. On the basis of theoretical and practical studies, a cone model has been proposed to response CO2degassing for the contact metamorphism, and it can be used to explore CO2accumulations beyond the oil‐gas basins. This model can also be applied to the study of inorganic genesis of CO2accumulations.