Abstract: Using fruit of Osmanthus fragrans lour as raw materials,water soluble polysaccharides from Osmanthus fragrans lour were extracted,and its antibacterial effect were studied in this paper.To obtain the extraction process of polysaccharides from Osmanthus fragrans lour fruit,single factor experiments and orthogonal experiments were done about solid- liquid ratio,extraction temperature,extraction time,extraction times,and meanwhile the purification efficiency of polysaccharides were studied by ethanol precipitation,and the antimicrobial activity of polysaccharide was studied by filter paper discs method and turbidimetric method. The results showed that the optimum extraction conditions of polysaccharides from Osmanthus fragrans lour fruit were as follow: Solid- liquid ratio 1∶ 30( g / m L),Extraction temperature 75 ℃,Extraction time 120 min,Extraction times 2.in which the extraction rate of polysaccharide from Osmanthus fragrans lour fruit was 3.67%. 5 times the volume of the ethanol of the extract could precipitate polysaccharides of Osmanthus fragrans lour fruit about 3.14%. Polysaccharides of Osmanthus fragrans lour fruit could inhibit the growth of Staphylococcus aureus,Bacillus subtilis,Escherichia coli,and the order of inhibition is Staphylococcus aureus,Bacillus subtilis,Escherichia coli.Under the incubation time of10~20 h and p H6 polysaccharides of Osmanthus fragrans lour fruit had a strong inhibition activity on the three bacteria,and the minimum inhibitory concentration of polysaccharides of Osmanthus fragrans lour fruit on the three bacteria were about 3.2%,3.2%,7.5%,respectively.