Qi-Ⅲ gold deposit, along with Hatu and Qi-ll in the west and Qi-IV, Baobei and Huilvshan in the east, consti- tute Hatu metallogenic belt. The host tuffaceous rocks were widely altered by sericitization, silicification, carbonation, py- ritization and arsenopyritization. The diagenetic and ore-forming process can be divided into seven stages: framboid stage (I), muscovite-quartz stage (II), isolated pyrite stage (II1), sulfide-gold stage (IV), calcite-pyrite stage (V), ankerite-albite stage (VI) and quartz-calcite stage (VII). The content of arsenic in hydrothermal pyrite has negative relationship with the content of sulfur. Pyrites in stage V contain nearly no arsenic. The tufts with distinct alteration intensity are enriched in LREE. All intensely altered samples are depleted in Cs, Rb, La, Ce, Ti, V, Cu and Zn, suggesting remobilized by hydro- thermal fluids. Cr, Ni and Mo were taken into the host rock by fluid. The temperature of sulfide-gold stage (IV) is 301℃ - 340℃, and the sulfur fugacity is -8.1- -10.8, higher than Hatu but lower than Baobei gold deposit, implying that the depth of ore become deeper from west to east.