Abstract: The paper studies the mode of gold in arsenopyrite (Asp) of Huangjindong gold deposit, Hunan Province. The special X-ray scanning is applied to approach the existing state of invisible gold in Asp, and analysis condition is investigated. Back scatter electron image is firstly used to determine whether grain-gold occurs, then, using LIF crystal for measurement of AuL=88.76 Lal peak. The selected Au-bearing Asp (without visible gold) is continuously analyzed by means of special X-ray at increasing magnification(×300、× 1000、×5000、×30000、×200000). It is found that gold element always evenly distributes in Asp. The result suggests that gold exists as lattice-Au mode in arsenopyrite.