To address the development demands for carbon emission reduction technologies in the cement industry and the design of oxy-fuel combustion calciners, this study investigated the effect of high-concentration CO₂ on cement raw meal decomposition under oxy-fuel combustion conditions by using thermogravimetric analysis (TGA). Two raw meal samples from an existing production line of a domestic cement plant were investigated, the key parameters including weight loss curve, weight loss rate, decomposition temperature and decomposition time of the raw meal were measured at a heating rate of 10°C/min. In addition, the decomposition characteristics of the above-mentioned raw meal under oxy-fuel combustion conditions were compared with the experimental results of the raw meal samples from another cement plant. The results show that with the CO2 concentration increasing from 30% to 90%, the initial decomposition temperature and complete decomposition temperature of the raw meal increase continuously. This is mainly due to the thermodynamic inhibition effect of high CO2 partial pressure on CaCO₃ decomposition, which requires increasing the temperature to offset this effect. After replacing air with O2-CO2 mixed gas, the complete decomposition temperature of the raw meal increases by about 60℃~100℃. Meanwhile, the complete decomposition time of the raw meal is shortened to 4~6min under the high-concentration CO2 atmosphere, because the elevated temperature improves the reaction kinetic rate, which partially offsets the thermodynamic inhibition effect of CO2. Moreover, the decomposition temperature of raw meal samples from the two plants is about 940℃ under the CO2 concentration of 80%.