The relationship between electromagnetic frequency and microstructures of continuous casting aluminum alloyswas studied. 7075 aluminum alloy ingot of 100 mm in diameter was produced by electromagnetic continuouscasting process, the microstructures of as-cast ingot was examined by scanning electron microscopy (SEM) equippedwith energy dispersive spectrometer (EDS). The results showed that electromagnetic frequency greatly influencedsegregation and microstructures of as-cast ingot, and product quality can be guaranteed by the application of aproper frequency. Electromagnetic frequency plays a significant role in solute redistribution; Iow frequency is moreefficient for promoting solution of alloying elements.