Abstract：A gold mask (K5:3) was unearthed from Pit No. 5 in the sacrificial zone of the Sanxingdui Site, though it was severely deformed upon discovery. Based on analyses of its material, burial environment, and deterioration conditions, a targeted conservation and restoration plan was developed and successfully implemented. The mask after restoration weighs 280g, with a remnant height of 25.47cm and remnant width of 27.8cm. It was fabricated with a gold-silver alloy containing 84.47% to 85.33% of Au and 13.8% to 14.25% of Ag. Regarding the fabrication process, it was supposed to be heated and hammered into a thin piece of gold and gradually take shape through cutting, engraving and percussion. After polishing, the outline is highlighted. The gold mask was likely not used independently but rather affixed to a bronze head or a mask of other material. It is by far the largest and heaviest gold mask ever found in the Sanxingdui Site, providing new material for the study of the Sanxingdui Culture. Its restoration presents vital experience for the repair of ancient gold artifacts in China.