For the billet, the electromagnetic stirring has the effect of uniform flow field and temperature in the mold, and the liquid surface of steel slag is a rotating paraboloid under electromagnetic stirring . In this paper, the cross section of a factory is 410 mm × 530 mm billet mold as the prototype, a three-dimensional numerical model was established by using ANSYS finite element software to study the influence of electromagnetic stirring on the flow field and temperature field of the mold. The maximum tangential velocity of molten steel increases with the increase of current and decreases with the increase of frequency. When the current of electromagnetic stirring increases from 0 A to 500 A, the fluctuation of liquid level increases from 1.21 mm to 4.35 mm. Electromagnetic stirring can make the high temperature zone of molten steel confined to the upper part of continuous casting mold and make the temperature of molten steel more uniform. Comprehensive analysis shows that the reasonable current of electromagnetic stirring is 400 A and the frequency is 1.5 Hz. At this time, the fluctuation of slag level is about 2.73 mm and the temperature field is more uniform.