Static simulation experiment is done for the Sn-3.5%Pb alloy of low-melting point to verify the effect of inner traveling magnetic field on the solidification microstructure of hollow tubular billet by continuous casting. The results show that the traveling magnetic field can provoke the circulation flow in the vertical section of molten metal, reduce the temperature gradient of solidification front and the cooling rate of molten metal, facilitate the transition from columnar to equiaxed structure, and refine the grains. So, the solidification microstructure of hollow tubular billet by continuous casting.was improved by the inner traveling magnetic field.