In order to resolve the lack of thermodynamic information for the comprehensive unilization of Ti-bearing blast furnace slag, the phase diagram relevant to the Ti-bearing slag composition was widely investigated. In the present work, the phase equilibrium relationships were investigated for the CaO-SiO₂-5wt.%MgO-20wt.%Al₂O₃-TiO₂ phase diagram system. The equilibrium phases were experimentally determined at 1300°C and 1400°C using the high temperature equilibrium technique followed by X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectroscope (EDX) analysis. The liquid phase (L), melilite solid solution ((2CaO·MgO·2SiO₂, 2CaO·Al₂O₃·SiO₂)_ss) phase, perovskite (CaO·TiO₂) phase, Al–Ti diopside phase and pseudobrookite solid solution (MgO·TiO₂, Al₂O₃·TiO₂)_ss phase were found. Based on the experimental results, the 1300°C to 1500°C liquidus lines and phase diagram were constructed for the specified region of the CaO-SiO₂-5wt.%MgO-20wt.%Al₂O₃-TiO₂ system.