The invention provides a method for reinforcing bacterial preoxidation of an arsenic-containing gold ore. Two additives (separately silver nitrate and ferric sulfate or ferric nitrate) are added. When being in use, a chloride-free 9K solution is prepared with the concentration of Ag(I) and Fe(III) reaching 0.005-0.05 g/L and 1-10 g/L respectively; then the arsenic-containing gold ore is added to the solution; and finally, a certain amount of a bacterium liquid is inoculated to the system for bacterial preoxidation. Under the synergistic effects of Ag(I) and Fe(III), the bacterial oxidation rate of the arsenic-containing gold ore can reach higher than 90%; and oxidation time is greatly shortened. On one hand, the synergistic reinforcement of Ag(I) and Fe(III) accelerates the dissolution of the arsenopyrite; on the other hand, toxicity of As (III) in the system toward to the bacteria is lowered, so that the bacterial oxidation of the arsenic-containing gold ore is reinforced; and important theoretical and technical guidance for increasing efficiency bacterial preoxidation-cyanide gold leaching process of the gold ore.