Abstract: Polysaccharide of pomegranate seeds and sodium sulfite as raw materials,contents of Se in synthetic product and yields of synthetic product as investigation index,raw material ratio,reaction temperature,concentration of HNO₃ and reaction time as experimental factors,the synthesis conditions were optimized by single factor test and Box-Behnken experimental designs,and simultaneously the product structure and antioxidant capacity were studied. The results showed that,the optimum preparation conditions of selenium polysaccharide ester of pomegranate seeds were as follows:Raw material ratio was 1:1.02,reaction temperature was 76 ℃,concentration of HNO₃ was 0.74%,and reaction time was 9.3 h. Under this conditions,contents of Se in synthetic product was(4.117±0.02) mg/g,and yields of synthetic product was 42.596%±0.13%. UV,IR and TGA analysis fully confirmed that selenium polysaccharide ester of pomegranate seeds contained Se=O,Se-O and Se-C. Synthetic product had a certain antioxidant capacity,so it could significantly slow the trend of oil POV value increasing trend,and had a certain amount of concentration-dependent manner. The study provided a theoretical basis for the full development and utilization of pomegranate seeds resources.