The effects of the different power, casting rate, quantity of cooling water and trace amount of Sc to 5356-Al alloy are investigated. The experiment shows 5356-Al alloy has the optimal surface and internal quality and tensile properties with the process parameters which the power is 10kw, the casting speed is 8-9cm/ min, the quantity of cooling water is 1.7m3/h. The tensile strength and elongation of 5356-Al alloy can be up to 310.0MPa and 16.3%, and the surface has no obvious casting defects. At the same time, the microstructure of the edge is equiaxed crystals basically, while the center is broken dendrite crystals with an uniform distribution of the second phases. Besides, the homogenization heat-treatment of 5356-Al alloy has also been established: 440℃?30h with the air cooling. After the homogenization heat-treatment, the micro-segregation of Mg has been eliminated basically and the phase Al8Mg5 which is distributing along the grain boundaries continuously dissolves significantly. In addition, trace amount of Sc can significantly improve the strength and plasticity of 5356-Al alloy. The experiment proves 5356-Al 0.4wt. %Sc alloy can refine the grain size and reduce the number of the second phase, the tensile strength and elongation can be up to 330.0MPa and 29.0%, which increased by 6.5% and 77.9% respectively.