Electroplating wastewater contains high levels of Fe and Mn. One of the treatment methods to remove Fe and Mn in electroplating wastewater is the aeration method using a cascade aerator. the aeration method using a cascade aerator. Aeration is the process of adding oxygen to the water so that it can cause oxidation reactions of Fe and Mn, which will form precipitates. and Mn, which will form Fe(OH)3 and MnO2 precipitates. The gas transfer coefficient (KLa) value during the aeration process was then determined. The Fe and Mn levels before the aeration process were 9.84 mg/L and 4.78 mg/L, respectively. obtained the highest decrease in Fe levels at 240 minutes with a flow rate of 90 mL/s with an efficiency of 70.63% and the highest decrease in Mn levels occurred contact time of 300 minutes with a flow rate of 90 mL/s with an efficiency of 62.76%. 62,76%. The highest gas transfer coefficient (KLa) value occurred at a contact time of 300 minutes with a flow rate of 90 mL/s of 0.0975 KLa/min. The research results obtained have met the quality standards of wastewater according to the Regulation of the Minister of Environment No. 5 of 2014 on Wastewater Quality Standards