6063 aluminum alloy samples with varied RE additions were prepared by strictly controlling pouring process and squeezing casting parameters

and tensile testing and micro-hardness testing for the samples prepared were carried out.Optimized composition design was conducted by orthogonal method.In addition

microstructure of the as-cast alloy was observed by OM（optical microscope） and SEM（scanning electron microscope） to understand the role of RE in the alloy.The result shows that the Al-0.5Mg-0.38Si-0.2RE alloy exhibits desirable mechanical properties.Meanwhile

the grains size in the alloy can be refined

and size and morphology of precipitate can be improved effectively.The mechanical properties of 6063D-RE alloy can fully meet requirements of the national standard.