In the field of electronic packaging， Au-Sn eutectic alloy （AuSn20） serves as key solder materials， and its preparation process directly affects the packaging performance and reliability. However， due to the brittleness of AuSn20， there is currently no efficient method for the preparation of AuSn20 solder balls. This study uses pulsated orifice ejection method to achieve the high precision and consistency of the on-demand preparation of AuSn20 solder balls. The results show that various specifications of AuSn20 solder balls are prepared under optimal process conditions， with the smallest specification being 50 μm， and the maximum standard deviation of the target particle size being 1.58 μm， significantly improving the preparation accuracy. Microstructural analysis reveals that the solder balls are mainly composed of δ-AuSn and ζ'-Au₅Sn eutectic phases， with no abnormal new phases observed. After reflow treatment， the composition distribution inside the solder ball tends to be uniform.Interface reaction studies show that due to the synergistic diffusion of Ni atoms in the diffusion barrier layer， a complex intermetallic compounds （Au，Ni）Sn and （Au，Ni）₃Sn₂ are formed at the interface joint. The AuSn20 solder balls prepared in this study not only achieve precise control of particle size and consistent thermal history， but also show excellent interface stability and structural integrity under simulated service conditions， opening up new application avenues for Au-Sn alloy brazing materials in advanced electronic packaging.