Due to the important effect of Al2O3 addition to the phase change in Ti-bearing slag system, the phase equilibrium relationships were investigated for the CaO-SiO2-5wt.%MgO-30 wt.%Al2O3-TiO2 phase diagram system with high Al2O3 content. The equilibrium phases were experimentally determined at 1400 °C and 1450 °C using the high temperature equilibrium technique followed by X-Ray Fluoroscopy (XRF), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectroscope (EDX) analysis. The gehlenite phase (2CaO·Al2O3·SiO2), perovskite phase (CaO·TiO2), spinel phase (MgO·Al2O3), Ti-rich diopside solid solution phase and anosovite solid solution phase were found. Based on the experimental results, the 1400 °C and 1450 °C isotherms and phase relations were obtained for CaO-SiO2-5wt.%MgO-30 wt.%Al2O3-TiO2 system relevant to high Al2O3 Ti-bearing slag system.