Response surface methodology based on single-factor experiment was applied to optimize the extraction conditions of polysaccharide. As a result, the optimum extraction conditions were extraction temperature 65 ℃, ultrasonic time 22 min, liquid to material ratio of 221 （mL/g）. Under the control of such conditions, the extraction rate of polysaccharide from Radix Glehniae was 12.13%. The polysaccharide from Radix Glehniae had typical characteristics of polysaccharides, containing 90.4% of the total sugar and 1.22% protein, and the thermal degradation temperature was 300.32 ℃. The scavenging abilities of DPPH free radicals (IC₅₀=1.99 mg/mL), OH free radicals (IC₅₀=1.71 mg/mL) and the inhibiting ability of α-glucosidase (IC₅₀ =5.23 mg/mL) were investigated. The results showed that polysaccharide from Radix Glehniae had certain free radicals scavenging and potential hypoglycemic activities.