To improve the efficiency of harvested quinoa seed wash processing, this study comparatively evaluated the effects of ultrasound-assisted hydration (UH) and conventional hydration (CH) on hydration dynamics, saponin mass transfer kinetics, and pericarp structural changes in quinoa seeds. Moisture uptake was monitored using a gravimetric method, saponin content was determined through enzyme-linked immunosorbent assay, and pericarp structural changes were observed via scanning electron microscopy. The results showed that UH significantly enhanced the water absorption rate of quinoa seeds, with the Peleg model effectively fitting all hydration stages (R