Ammonia nitrogen in electrolytic manganese residue limits its resource utilization. The combination of citric acid and red mud can efficiently and completely remove ammonia nitrogen from electrolytic manganese residue. In this paper, the effects of process conditions such as dosage of treatment agent, reaction time and leaching method on residual concentration of ammonia nitrogen in electrolytic manganese residue are studied. The substance changes are characterized by XRD and XPS techniques and the mechanism of ammonia nitrogen removal is discussed. The results show that the leaching process of citric acid involves oscillation leaching for 30 minutes under citric acid dosage of 25% and liquid-solid ratio of 5:1. The deep removal process of red mud involves leaching at room temperature for 5 hours under electrolytic manganese residue to red mud mass ratio of 1:0.5, and the residual concentration of ammonia nitrogen is reduced to about 1mg/L. The ammonium ions in the leaching solution react with citric acid to form ammonium ferric citrate, which is stabilized in the leaching solution. The alkaline substances in the red mud react with the residual ammonia nitrogen, and the ammonia nitrogen is removed in a gaseous form.