Abstract: This study established an optimized ultrasound-assisted deep eutectic solvent (DES) extraction method for polysaccharides from Pleioblastus amarus (Keng) Keng f. shoots and systematically evaluated their structural characteristics and in vitro bioactivities. Using a choline chloride-lactic acid DES system (molar ratio 1:3) under optimized conditions (liquid-solid ratio 30:1 mL/g, ultrasound time 40 min, power 75 W, temperature 40 ℃), a polysaccharide yield of 12.73% was achieved. Structural characterization indicated the extracted polysaccharides had a weight-average molecular weight of 381.52 kDa, composed primarily of arabinose, galactose and glucose, with characteristic polysaccharide functional groups and an amorphous honeycomb-like porous morphology. In vitro bioactivity assays demonstrated that the polysaccharides from bitter bamboo shoots possess excellent antioxidant capacity, with IC₅₀ values of 0.51 mg/mL (DPPH radical scavenging), 1.80 mg/mL (ABTS⁺ radical scavenging), and 0.86 mg/mL (ferric reducing antioxidant power). The polysaccharides also exhibited potential for lowering blood lipids and blood glucose. At a concentration of 2 mg/mL, they inhibited α-amylase activity by 36.6%; at 3 mg/mL, the binding rates to sodium taurocholate and sodium glycocholate were 52.10% and 46.18%, respectively. Furthermore, the polysaccharides showed inhibitory effects against Bacillus subtilis, Escherichia coli, and Staphylococcus aureus, with inhibition zone diameters exceeding 10 mm. This study provides theoretical foundations for optimizing extraction and developing functional applications of Pleioblastus amarus (Keng) Keng f. shoot polysaccharides.