The Institute of Mechanics, Chinese Academy of Sciences, has completed weightless flight tests for space metal manufacturing technology in Xi'an, conducting over 20 effective parabolic zero-gravity flights. The tests covered materials including stainless steel, titanium alloys, aluminum alloys, and high-entropy alloys, yielding critical data on alloy melting and solidification behavior, melt pool evaporation, and defect formation under low-gravity conditions. This formally completes the four-tier experimental validation system of "drop tower — zero-gravity aircraft — rocket — in-orbit platform." Results indicate that the powder route for space metal 3D printing faces higher engineering thresholds in microgravity — weightlessness imposes control requirements on powder feeding, spreading, and melt pool stability that differ significantly from those on the ground. Value for powder buyers: ① In-orbit manufacturing imposes requirements on powder flowability, sphericity, and electrostatic control that do not exist on the ground; ② Data accumulated through the four-tier validation system will feed back into ground-based powder quality control standards; ③ With the rise of commercial space and in-orbit manufacturing, "space-grade" quality control capability will become a new competitive edge for high-end powders and can serve as a differentiating selling point when serving aerospace customers.