In order to study the technology and activity of carboxymethylated polysaccharide of wild jujube， the carboxy methylation process of wild jujube polysaccharide was optimized by response surface analysis method， and the bioactivity activity of wild jujube polysaccharide in vitro was studied. The optimum conditions were as follows: reaction temperature was 80 ℃， concentration of NaOH was 2.5 mol/L and chloroacetic acid was 3%. The carboxy methylation of wild jujube in vitro activity showed that the total reducing power of 5 mg/mL solution was 1.295， the scavenging rate of DPPH and hydroxyl radicals was 81.9% and 95.8%， respectively. The results of polysaccharide on probiotics indicate that the growth promoting effect of the polysaccharide was related to the concentration of the polysaccharide.