The techniques for warter extraction-ethanol precipitation of polysaccharide from Malus micromalus Makino were optimized by using the orthogonal test and single factor test.Meanwhile,the antibacterial activity of polysaccharides from Malus micromalus Makino was tested by double-layer agar diffusion method.The results showed that solid-to-liquid ratio and extraction temperature influenced the extraction efficiency of polysaccharides from Malus micromalus Makino,respectively.The optimal extraction conditions were identified as follows:1∶ 25(g∶ mL) solid-toliquid ratio,90℃ extraction temperature,60 min extraction time,80% ethanol concentration.Under the optimized conditions,the content of polysaccharide from Malus micromalus Makino was 105.15 mg /mL.The antibacterial activities were revealed against Bacillus cerecus CGMCC1.168,Saccharomyces cerevisiae and Listeria monocytogenes CMCC54002,with minimum inhibitory concentration(MIC) of respectively 25 mg /mL,25 mg /mL,50 mg /mL.