Cortex Dictamni polysaccharides (CDPS) was isolated from Cortex Dictamni,and was purified through DEAE column to obtain two kinds of polysaccharides (CDPS-1 and CDPS-2).The molecular structure of CDPS was characterized,and the anti-allergic activity was investigated.The molecular weight,monosaccharide composition and glycosidic bond type of CDPS-1 were analyzed by high performance gel filtration chromatography (GFC),ion chromatography (IC) and infrared spectroscopy (IR).CCK-8 was used to evaluate the toxicity of CDPS to RBL-2H3 cells.C48/80 as an irritant induces RBL-2H3 cells to degranulate and release β-hexosidase (β-HEX).So,the anti-allergic activity of CDPS can be evaluated by inhibiting the release of β-HEX from RBL-2H3 cells induced by C48/80.The protective effect of CDPS on cell membrane was assessed by improved erythrocyte hemolysis test.The CDPS anti-oxidation was investigated through scavenging DPPH free radical.The results showed that CDPS-1 was mainly composed of fucose,glucose,xylose,rhamnose and galactose with the molar ratio was 0.41∶1.38∶3.15∶15.4∶79.61.The relative molecular weight of CDPS-1 was 2 577 Da.When the concentration of CDPS-1 was 1 mg/mL,the inhibition rate of CDPS-1on β-HEX release from RBL-2H3 cells was 28.54%.At the concentration of 5 mg/mL,the hemolysis inhibition rate of red blood cell (RBC) under the protection of CDPS was 62.1%.When the concentration was 10 mg/mL,the scavenging rate of CDPS to DPPH was 40.06%.The results show that CDPS has an anti-allergy ability and has potential application in cosmetics.