The influence of electromagnetic parameters (the distance between upper and lower poles and the coil current intensity) on the flow field in the mold and the volatile behavior of steel/slag interface was studied by numerical simulation. The results show that the magnetic induction intensity in the covered area of the upper magnetic pole and the lower magnetic pole in the full?amplitude two?stage electromagnetic brake crystallizer affects each other. The increase of the current intensity in the coil of the upper (or lower) magnetic pole will lead to the increase of the magnetic induction intensity in the covered area of the corresponding lower magnetic pole (upper magnetic pole). The full amplitude two?stage electromagnetic brake can significantly restrain the flow velocity of molten steel and stabilize the fluctuation of meniscus in the mold. As the distance between upper and lower magnetic poles increases, the impact intensity of molten steel jet on the narrow surface of the mold increases, and the turbulent kinetic energy and velocity of molten steel at the steel/slag interface increase. With the increase of the current intensity of the upper magnetic pole coil, the impact intensity of liquid steel jet on the narrow surface of the mold is basically unchanged, and the flow velocity and turbulent kinetic energy of liquid steel at the steel/slag interface decrease. As the current intensity of the lower pole coil increases, the impact intensity of liquid steel jet on the narrow surface of the mold decreases slightly, and the flow velocity and turbulent kinetic energy at the steel/slag interface decrease.