The catalytic effect of Cu²⁺ on the bio-oxidation of arsenopyrite was studied through experiment to solve the surface passivation of arsenopyrite during its bio-oxidation process.The variation of Fe and As concentration,pH,and Eh in the bioleaching solution was analyzed during the leaching process.And the leaching residue was characterized by XRD and SEM.The experimental results show that Cu²⁺ can enhance the bioleaching rate especially at suitable concentration,shortening the oxidation cycle by 10 d.The added Cu²⁺ can enter into the passivation layer formed by orpiment and realgar to participate in the reaction,accelerate the dissolution of the passivated materials,and crack the dense passivation film,thereby facilitating the oxidation of the arsenopyrite.