A three-dimensional numerical simulation has been performed to understand the motion of the melt flow and thermal field during the Czochralski silicon single crystal growth process under the influence of a transverse magnetic field. With the application of a transverse magnetic field, the velocity, temperature and oxygen concentration fields in the melt become three-dimensional and asymmetric. Stronger downward flow motion is formed under the melt-crystal interface which can prevent the movement of oxygen impurities towards the melt-crystal interface. This may explain why the presence of a transverse magnetic field decreases the oxygen concentration level along the melt-crystal interface. The uniformity of the oxygen concentration at the melt-crystal interface is also improved when the magnetic field is applied. There is an increase in either the crystal diameter or the crucible rotation rate, and the oxygen concentration level becomes greater. The uniformity of oxygen concentration is better for higher crystal diameters, (C) 2014 Elsevier B.V. All rights reserved.