Semiconductor-grade monocrystalline silicon is the basic material for the integrated circuit industry and its quality determines the performance of chips. The distribution of oxygen content in Czochralski (Cz) silicon crystals has an important impact on the quality of silicon wafers. The oxygen content distribution during crystal growth can be effectively controlled by optimizing the heat shield structure of the furnace, but it is difficult to investigate the intrinsic mechanism through experiments. In this study, effect of the structure of heat shield on the distribution of oxygen content in 200 mm semiconductor-grade Cz monocrystalline silicon was investigated by ANSYS finite element analysis. Single-section and two-section heat shield structures are widely used in commercial furnace, by comparison, the distribution of temperature and flow fields, the temperature gradient at the solid-liquid interface and the radial oxygen content distribution for different stages of body growth (300, 800, 1 000 mm) were analyzed. The simulation results demonstrate that the temperature field uniformity of the single-section heat shield structure is better than that of the two-section heat shield structure, the temperature gradient at the solid-liquid interface in the former is smaller. Also, the low argon flow rate is favorale to the volatilization of SiO gas, and weakening the shear convection of the melt, leading to an inhibition of diffusion movement of oxygen from melt to crystal. Therefore, the radial oxygen content distribution at the solid-liquid interface is more uniform and the oxygen content in the crystal is lower under the condition of the single-section heat shield structure than that of the two-section heat shield structure.