Abstract: OBJECTIVE On the basis of single factor experiment, to optimize the extraction process of polysaccharide from Herba Patriniae by ultrasonic composite-enzyme method by orthogonal experiment. To analyze and evaluate the preliminary structure and the antibacterial activity of Patriniae polysaccharide through instrumental analysis and antibacterial test in vitro, respectively. METHODS The effects of enzyme dosage, solid-liquid ratio, ultrasonic power and time on the extraction rate of polysaccharides were investigated by the four-factor, three-level orthogonal test, while the structure of polysaccharide was analyzed using high-performance gel permeation chromatography, gas chromatography, ultraviolet and infrared spectroscopy. RESULTS The optimum extraction conditions of Patriniae polysaccharides were as follows:extraction temperature 50℃, pH=6.5, enzyme dosage 2.0%, solid-liquid ratio 1:20, ultrasonic power 90 W, ultrasonic time 20 min. Under the optimum conditions, the extraction yield of Patriniae polysaccharides was (25.01±0.15)%, while the concentration of total carbohydrate was (44.12±0.14)%. Ultraviolet spectroscopy analysis showed that the purity of Patriniae polysaccharide was higher after purification by gel column chromatography. Infrared spectroscopy and gas chromatography analysis showed that Patriniae polysaccharide was a furan-type glycoside ring skeleton with α- and b-glycosidic bond, and was mainly composed of glucose, mannose, galactose, arabinose, rhamnose and xylose at the molar ratio of 1:0.5:0.9:1.1:0.3:0.3, with the average molecular weight 1.26×10⁵. Antibacterial test in vitro showed that the Patriniae polysaccharide had certain antibacterial activity against Klebsiella pneumonia (K. pneumonia) and Pseudomonas putida (P. putida), but no antibacterial effect on Bacillus cereus (B. cereus) and Micrococcus luteus (M. luteus).CONCLUSION Ultrasonic-composite enzyme is an efficient extraction method, and the extracts rich in polysaccharide, with certain antibacterial activity.