Hg3In2Te6 (MIT for short) is a stable phase corresponding to x=0.5 in the Ⅱ-Ⅵ/Ⅲ-Ⅵ compound semiconductor Hg(3-3x)In2xTe3. In this paper, the stability and doping efficiency of Au in MIT were systematically investigated using the first-principles method. The results show that Au-Te bonds has polar covalent bond characteristics similar to that of Hg-Te bonds in MIT, indicating that Au has certain doping stability in MIT. In addition, it is found that there are amphoteric doping properties of Au in MIT: Au exhibits acceptor properties in AuHg and AuIn systems, and the Au-5d electron orbital resonates with the Te-5p electron orbital at the top of the valence band and -4 eV position, respectively, forming acceptor defect levels. While Au exhibits donor characteristics in AuTe and AuI systems, Au-5d resonates with Hg-6s and In-5s electron orbitals at the conduction band bottom, forming donor defect levels. It is worth noting that under Hg-rich conditions, there will be a self-compensation effect between AuI, AuTe and AuHg systems, and the Fermi level will be pinned at the top of valence band, while under Te-rich conditions, the self-compensation effect will be effectively eliminated.