A simulation model was developed to investigate the effect of rotating electromagnetic stirring on the solidification process of clad hollow billets during horizontal continuous casting.Two cases with and without rotating electromagnetic stirring were compared in detail using the simulations.When rotating electromagnetic stirring is applied, the flow pattern of fluid melt is greatly modified;the mushy zone becomes much wider and the temperature profile becomes more uniform for both the external and internal alloy melt layers.These modifications are beneficial for improvement of the microstructure of the clad hollow billet.