The application of a horizontal magnetic field is an important method for controlling point defects and impurity distribution in 12-inch Czochralski silicon used in integrated circuits. This work introduces the effects and mechanisms of horizontal magnetic field positioning on oxygen concentration in 12-inch single crystal silicon used for commercial integrated circuits. Effect of melt convection, and temperature distribution on oxygen concentration at the bodying length of 500 mm was presented and analyzed by combining growth experiments and numerical simulations (using CGSim_23_2 from STR) with different horizontal magnetic field positioning. This study found that the mechanism of magnetic field control of oxygen is not directly correlated with the convection suppression effect. It is important to avoid the overlap of strong magnetic regions with high-temperature areas, as this can lead to additional oxygen dissolution.