Double-stream-pouring continuous casting (DSPCC) is a novel technique to prepare gradient composites. In this paper, a two-dimensional steady mathematical model coupled flow, heat and solution transport in the solidification zone of DSPCC has been established based on the standard k-ε turbulent model. The variation of thermo-physical properties of the alloys against the temperature is also considered. The effects of casting speed on the temperature field, velocity field and composition of the researched composite are analyzed based on the proposed mathematical model. An experimental 2024/3003 aluminum composite was prepared by using a laboratory-made DSPCC facility. Selected results of experiment are in a good agreement with that of numerical simulation.