Lightweight material R&D is an important topic of product innovation. To fabricate a product with a complex lightweight design, 3D printing technology is one of the efficient candidates. However, the most used lightweight materials, such as Al 6061 or Al 7075, are challenging to be printed due to the severe hot cracking issue. Hence, scalmalloy was developed to overcome this issue. However, some challenges must be overcome before such materials can be widely used due to changes in processes, materials, and design from conventional methods to additive manufacturing technologies. That is, it is difficult to achieve high densification, defect limitation, and microstructure control during the additive manufacturing process at the same time. Hence, it is essential to explore a methodology to optimize the 3D printing parameters and further understand the relationship of the design-material-process-microstructure-property of the scalmalloy. In this study, the database of the parameters and microstructure was introduced to establish a simulation tool. With the help of the simulation tool, it was easier to explore the relationship between the parameters and melting pool behavior. Hence, the optimized parameter had been developed. Furthermore, the microstructure evolution and mechanical properties before and after the parameter optimization would be discussed in detail in this study.