This study targeted the agricultural soils in the Hetao irrigation area, combined with the stable carbon isotope technique to determine soil organic carbon (SOC), inorganic carbon (SIC), and CO₂ gas isotope value (δ¹³C value), to differentiate between lithogenic carbonate (LC) and pedogenic carbonate (PC), and finally to quantify the amount and source proportion of fixed CO₂ gas during the formation of PC formation, and finally quantify the carbon transfer from SOC to inorganic carbonate. The results showed that, in the 40–60, 60–80 and 80–100 cm soil layers, the proportion of PC was 46.59%, 28.09% and 30.39%, respectively, and the mass of PC was 35.88, 20.15 and 21.35 g/kg, respectively. During the formation and recrystallization of PC, the amounts of CO₂ fixed by the three soil layers were 7.73, 4.43 and 5.04 g/kg, respectively; among which, 4.43, 2.70 and 3.41 g/kg from the atmosphere, 3.30, 1.73 and 1.64 g/kg from soil respiration, respectively; which indicated the atmospheric CO₂ as the main contributor. The amount of carbon transferred from SOC to inorganic carbonate was 1.65, 0.87 and 0.82 g/kg, respectively. This study is a preliminary investigation of intra-soil carbon transfer, which is important for understanding soil carbon dynamics and maintaining ecosystem stability in the Hetao irrigation area.