Abstract: Leuconostoc sp.SK24.002 was firstly used to prepare water- soluble polysaccharide.The weight- average molecular weight of the water- soluble polysaccharide was 2.4 × 10 6 , and the molecular weight distribution was concentrated and not influenced by sucrose concentration.The main factors affecting the growth of strain and the yield of water-soluble polysaccharide were determined by single factor test.The main factors were sucrose 140g /L, yeast extract powder 3.75g /L, tryptone 3.75g /L, inoculation 5% , medium initial pH7.5, fermentation temperature 30℃ and volume of medium 100mL /250mL.The maximum productivity was 51.40g /L at 20h under this condition.