Reduction Disintegration Index ( RDI) is one key factor of sinter quality, which indicates the degree of disintegration by the reducing gas at about 550 in the middle of the blast furnace shaft. This is related to the permeability and reduction reaction between gas and sinter in the blast furnace, so appropriate quality control is essential. RDI is influenced by chemical composition such as slag volume, basicity (CaO / SiO2), MgO, Al2O3 and FeO. Amongst these, Al2O3 and FeO vary the most depending on the type of iron ore and the operating conditions. Therefore, it is necessary to quantitatively evaluate the effect of Al2O3 and FeO changes on RDI under Hyundai-Steel Companys sintering process conditions. The decrease of FeO of 0.1% in the sintered ore was found to increase sinter RDI by about 0.2%. Since FeO in the sintered ore is determined by the sintering reaction, it can be controlled by changing the operating conditions. When the content of Al2O3 in the raw sinter mixture was lower than 1.95%, RDI increased by 0.1% with incremental 0.1% increases in Al2O3 from 1.5%. When Al2O3 content was higher than 1.95%, RDI increased 0.5% with 0.1% increments in Al2O3. The works refer to that control of sinter RDI at high Al2O3 contents of greater than 1.95% will be very difficult for the plant operator. It was however possible to achieve RDI control by correcting basicity and MgO contents of the raw sinter mixture. CITATION:Won, S Y, Choi, J H, Oh, J M, Yoon, H J and Kim, J H, 2019. Effect of Al2O3 and FeO composition on RDI in sintering process, in Proceedings Iron Ore 2019, pp 176181 (The Australasian Institute of Mining and Metallurgy: Melbourne).