The numerical simulation is combined with high‐temperature measurement to study the effects of electromagnetic braking (EMBr) and casting speed on the flow field, the fluctuation of the interface of the steel and slag, the distribution of argon gas bubbles, and the removal ratios of inclusions in the mold with a size of 1050 × 230 mm. The numerical simulation results and the high‐temperature measurement results of the velocities of molten steel at the 1/4 width and center of the thickness near the mold surface are in good agreement. The EMBr can reduce the velocity near the mold surface, the fluctuation of the interface between steel and slag, and the number of argon gas bubbles near narrow walls and decrease the total removal ratio of inclusions from 27.29 to 23.24%. When the casting speed is increased from 1.6 to 2.0 m min−1 with EMBr, the velocity of molten steel near the mold surface is increased. Even under the condition of a high casting speed of 2.0 m s−1, the velocity of molten steel near the surface is still in a reasonable range with EMBr. The total removal ratio of inclusions increases from 20.76 to 23.90%.