<p>The oxidation loss of Al and Ti during the electroslag remelting (ESR) of GH4169 Ni-based superalloy is a critical issue affecting its compositional homogeneity. In this study, slag-alloy equilibrium experiments were carried out to reveal the phenomenon of “Al oxidation loss and Ti increase” and the significant influence of temperature on element oxidation loss. A thermodynamic model based on the Ion and Molecule Coexistence Theory (IMCT) and the Wagner equation was developed to accurately predict the equilibrium contents of Al and Ti, clarifying the controlling roles of key components (CaO, Al₂O₃, and TiO₂) and temperature in the CaO-Al₂O₃-CaF₂-MgO-TiO₂ slag system. By further coupling the laws of energy and atomic conservation, a mathematical model was developed to predict the axial distribution of Al and Ti in the ESR ingots, achieving accurate predictions from laboratory-scale to industrial-scale ingots (Φ450 mm). Guided by the model, the slag composition was optimized and the slag amount was increased to 65 kg. The deviations in Al and Ti contents between the top and bottom of the industrial ingots were successfully controlled within 0.04 and 0.03 wt&#xa0;pct, respectively, significantly improving compositional homogeneity and providing an effective theoretical basis and practical guidance for precise composition control during the ESR process of superalloys.</p>