gradient aluminum alloy was prepared by semi-continuous casting using double-stream-pouring technique. The microstructures of the as-cast, pressed and heat-treated alloys were analyzed by scanning electron microscope and transmission electron microscope. And the mechanical properties of the alloy in pressed and heat-treated states were studied. The results show that the ingots with diameter of 65 mm and external thickness (about) 5.5 mm are obtained when the temperatures of the melt in the internal and external ladles are 1 023 and 1 003 K, respectively, and the nozzle diameter is 2.0 mm. The microstructures of the as-cast alloy consist of α(Al)+(θ(CuAl_2))+S(Al_2CuMg) in the internal region and (α(Al)+MnAl_6) in the external region. The phases found in the internal and external layers coexist in the transition zone. The transition layer is maintained after plastic deformation and heat treatment of the alloy. The tensile strength, yield strength and elongation of the alloy are 300 MPa, 132 MPa and 16.0%, respectively, after T6 treatment. The tensile and yield strength are increased by 150.0% and (94.1%,) respectively, compared with that of 3003 aluminum alloy. The maximum hardness in the internal region of 2024/3003 gradient aluminum alloy can be increased from HRF 55 in the pressed state to HRF 70 in the heat-treated state.