[Objective] The aim was to optimize the extraction process of polysaccharide from Laminaria japonica Aresch.by ultrasonic-aqueous two phase system assisted extraction.[Method]The acetone-ammonium sulfate system coupling with ultrasonic extraction was used to extract the polysaccharide from Laminaria japonica Aresch.,and the content of polysaccharide was determined with phenol-sulphuric acid.The single factor test was used to optimize the extraction process of polysaccharide.[Result]The optimum extraction co...