Abstract: Mechanism model of copper oxygen-enriched bottom blowing smelting (BBS) is constructed by analyzing smelting process deeply, combined with related theories of copper metallurgical process. Model’s cross section includes seven functional layers, i.e. gas layer, mineral decomposition transition layer, slag layer, slag formation transition layer, matte formation transition layer, weak oxide layer and strong oxide layer. Longitudinal section is divided into three functional regions, including reaction region, separation transition region and liquid phase clarification region. The layers or regions play different roles and constitute an organic unit. Ploycomponent, such as CuFeS₂, FeS₂, Cu₂S, FeS, 2FeO·SiO₂, Cu₂O, FeO, Fe₃O₄, SO₂, H₂O, N₂ and S₂, transfers quickly through the interface between different layers and regions, with the effect of character differentiation and fluid flow. BBS is at the state of dynamic non-steady multiphase equilibrium, and the value of oxygen and sulfur potential changes gradually in longitudinal and cross direction, and the capacity of BBS can be raised by reasonably controlling the potential value in different layers and regions.