Abstract: Chalcopyrite dissolution during gold cyanidation consumes excessive NaCN and dissolved oxygen, generating byproducts that inhibit gold leaching. This study investigates the regulatory mechanism of lead acetate (C₄H₆O₄Pb·3H₂O) on the cyanidation behavior of chalcopyrite. Cyanide leaching tests with varying C₄H₆O₄Pb·3H₂O dosages were performed, and interfacial property changes were characterized by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results demonstrated that a 0.03 g·g⁻¹ dosage of C₄H₆O₄Pb·3H₂O reduced NaCN consumption from 0.60 to 0.28 g and decreased thiocyanate ion concentration from 1833.5 to 813.5 mg·L⁻¹ after 24 h of leaching. Dissolved oxygen remained above 5.9 mg·L⁻¹, indicating suppressed oxygen depletion. XPS and ToF-SIMS confirmed a ~9 nm passivation layer composed of Pb(OH)₂, PbO, and PbS on the chalcopyrite surface, which inhibited the formation of CuCN, \textFe(\mathrmCN)_6^4- , and SCN⁻ species. This passivation layer significantly reduced copper and iron dissolution, lowering their concentrations by 569.2 and 16.5 mg·L⁻¹, respectively. These findings indicate that C₄H₆O₄Pb·3H₂O effectively mitigates the detrimental impact of chalcopyrite on cyanide leaching and optimizes the chemical environment for gold leaching.