Soybean residue is a rich byproduct that is discarded in soybean processing factories. In this research, soybean residue was used to prepare highly valued genistein by separation and purification through the combination of isoelectric point precipitation, centrifugation, solvent extraction, and macroporous resin adsorption. The purification process had been studied in detail. The results showed that AB-8 resin, feathering high adsorption and desorption recovery, is a suitable resin for purifying genistein, and a optimized process for gradient elution was obtained: the extracts was sequentially eluted with deionized water, 20% ethanol, and 70% ethanol in the first process, and with 40% ethanol and 70% ethanol in the second process; the purity of genistein was about 90% by high-performance liquid chromatography (HPLC) analysis.