Gold-based alloys were prepared by electromagnetic stirring and conventional die casting respectively. The effects of electromagnetic field on as-cast microstructure and central defects of gold-based alloy were investigated. The results show that the dendritic structure of the gold-based alloy billets prepared by electromagnetic stirring is more uniform and smaller than that by conventional casting, Meanwhile, Such defects as shrinkage cavity and porosity that frequently occur in the central region of gold-based alloy ingot produced by conventional die casting are eliminated. Moreover, the effects of electromagnetic stirring on the mechanism of refinement of the solidification structure and elimination of central defects were also discussed.