Abstract: Based on the vorticity and stream function equations with finite-element method, a mathematical model was developed to describe molten alloy flow in mold with two pairs of poles. The results from above model show there are four vortexes in mold with the present experimental condition. The faster the casting speed, the stronger the vortex intensity and nearer the divided flow point to the wall of mold, which deteriorates the erosion of the initial shell near narrow wall of mold. The erosion of initial shell will be weakened effectively with imposing of the two pairs of magnetic poles. The stronger the magnetic density and the better the braking effect. The two pairs of magnetic poles can make the velocity decrease and the vortex intensity weaken in the upper field of mold and stabilizes the meniscus fluctuation.