The efficient catalytic hydrolysis and mitigation of unstable structural transitions in lignin are essential for the commercialization of organic acid pretreatment. A novel binary carboxylic acid pretreatment utilizing α-ketoglutaric acid (AKA) was developed, which exploits a distinctive ion-pair biomimetic catalytic mechanism along with the activation of the ketone group. Under optimal AKA pretreatment conditions (5 % acid concentration, 150 °C, 45 min), the hemicellulose separation yield reached 85.21 %. The rapid and efficient separation of eucalyptus hemicellulose results from the low pKa value and the ion-pair biomimetic catalytic mechanism of AKA. The lignin structure exhibited greater integrity (β-O-4: 47.45 %) and a higher phenolic hydroxyl content (1.82 mmol·g