Structure of system of BaO - Al2O3-Fe2O3

System of BaO - Al2O3-Fe2O3 can be utilized for manufacturing the ferromagnetic ceramics as well as the binding materials for special purpose. Data on total structure of the system are absent. In connection with this, investigation of sub-solidus structure of the system have been performed at temperature of 1300SDGRWC. Results of the investigations have been presented. Thermodynamic analysis of the system and experimental investigations of the system have been carried out. This has made it possible to provide triangulation of the system taking into account all phases which are stable at the considered temperature and to determine its geometric characteristics.