Purpose Optimization of enzymatic extraction process for total polysaccharides from mulberry (Morus alba L.) leaves and comparison of biological activity before and after purification. Methods The polysaccharide from mulberry leaves was extracted by cellulase and the optimal extraction parameters were optimized by single factor and orthogonal experiment. The primary purification was carried out by Sephadex G-100. The antioxidant activity and α-glucosidase inhibitory activity of polysaccharides before and after purification were compared. Result The optimal process parameters was pH 6, enzyme concentration 1.0%, extraction temperature 50 ℃, time 50 min; total polysaccharides after purification had higher total antioxidant capacity and DPPH, hydroxyl radical scavenging capacity; but the inhibitory effect of α-glucosidase was lower than the before. Conclusion The optimized process parameters had better extraction effect, and the primary purified total polysaccharides had stronger antioxidant activity.