The Kaldo furnace smelting technology is a typical process for the comprehensive treatment of copper anode slimes. However, the reduction sequence of key components and the phase evolution mechanisms remain unclear. In this study, simulations are conducted to analyze the slag system and reduction thermodynamics. The phase evolution during the reduction smelting of decoppered anode slimes for the collection of precious and rare metals is investigated through microscopic characterization of the slag and noble lead samples.The results indicate that the reduction smelting of decoppered anode slimes primarily forms a PbO-Na2O-SiO2 ternary slag system containing PbSiO3 and Na2Si2O5 phases. The reduction sequence of elements is determined as Ag>Se>Te>Bi>Pb. The main phase evolution pathway of PbSO4 follows the sequence PbSO4→PbO?PbSO4→PbS→Pb. The noble lead phases consist of PbSe, BiSe, and AgTe, with no diffraction peaks corresponding to elemental single phases observed. SEM analysis reveals that Pb and Se share similar distribution regions, while Ag and Bi exhibit complementary distribution patterns. Te is uniformly distributed, whereas Ag, Bi, and Pb show concentrated distribution zones with phenomena of segregation and contrast differences. XPS results show that Pb, Ag, Bi and Te in precious lead have zero valence and positive valence, and the proportion of 0 valence is 64%, 88%, 52%, and 47%, respectively. In contrast, Se exists in 38% zero-valence state and 62% negative valence state (Se2-). Due to the uneven distribution of metal particles, the unaggregated metal particles Pb, Bi and Se mainly form PbSe and BiSe intermetallic compounds, and Ag and Te form AgTe. Combined with XRD and SEM characterization, it is shown that the smelting reduction process of copper anode slime mainly forms stable intermetallic compounds to realize the capture of rare and precious metals.