Numerical simulation and experimental studies were used to analyze the effect of spiral magnetic field with different exciting currents on the solidification process of the Pb-Sn alloy. The results show that with the increase of exciting current the spiral magnetic field can reduce the cooling rate and temperature gradient of molten metal, and facilitate the transition from columnar to equiaxed structure. The axial component of the force can enhance the circulation of the melt along the axial direction, which can promote dispersive distribution of the primary β phase and eliminate the macro-segregation. However, the strong stirring at large current increases the collision probability between the grains and the grains aggregate more easily while the increasing induction heat also delays the cooling rate of the molten metal, and then the size of grains becomes bigger. At f=10 Hz, there is a suitable range of exciting current within 100~125 A for refining grains and improving the macro-segregation.