Abstract: The hemicellulose in waste liquid of regenerated cellulose fiber was extracted by membrane separation,and the technical parameters and composition of hemicellulose were determined. The xylooligosaccharide was prepared by enzyme hydrolysis from the hemicellulose. The process parameters of enzymatic hydrolysis were determined by orthogonal experiment,and the composition and application performance of xylooligosaccharide were analyzed and measured. The results showed that the enrichment ratio was 3.5 times,the extraction rate of hemicellulose could reach 85% and the xylose content in hemicellulose could reach up to 79.2%. When the pH value was 5,the enzymatic hydrolysis temperature was 55 ℃ and the enzymatic hydrolysis time was 7 h,the yield of xylose oligomer could reach 36.2%. The test showed that the main component of the prepared xylooligosaccharide were xylotetrose,xylotriose,xylobiose and xylose,accounting for 90.7%. The performance index of the product met the national standard of feed grade oligosaccharide dry powder an had good application value.