Nowadays, aging is increasingly severe, and the incidence of bone defects has gradually increased. In addition, bone tissue engineering is a kind of advanced technology to overcome the shortcomings of traditional bone grafting methods. In terms of materials, metal has been treated as the best choice for producing orthopedic implants. Furthermore, through a part of the concept of bone tissue engineering and the introduction of porous structures, we can adjust the mechanical properties of metal materials so that Young’s modulus can match that of the surrounding human bones, which can avoid the stress shielding effect. Magnesium alloy is considered one of the better candidates among all metal biomedical materials due to its excellent biodegradability and biocompatibility. In terms of manufacturing, selective laser melting (SLM) has been regarded as the most suitable method for manufacturing metal porous materials. However, as a result of high activity as well as easy evaporation of magnesium alloy, there will be issues during the process, such as explosion and missing magnesium content. Since the above two issues are difficult to resolve, a new multi-step fabrication method, "negative salt pattern molding," has recently been developed. Nevertheless, this method still has disadvantages , which is with the increase of the distance from the infiltration point of NaCl paste, not only the degree of the shape accuracy will decrease, but also the deviation of the porosity will increase, and the irregular pore will become adverse effects on the growth of cells. Therefore, the purpose of this research is to improve the accuracy/precision and decrease the deviation of porosity by fabricating a negative salt pattern mold in the resin scaffold by precipitating NaCl layer by layer. After that, a porous magnesium alloy will be cast with the help of this mold.