Pomace was rich in dietary fiber.Sulfation treatment was applied to improve the biological function of water-soluble dietary fiber in pomace.After being bleached and extrusion,the water-soluble dietary fiber in pomace was extracted.Then,the sulfation treatment through amino acid-pyridine method was performed.Based on the singlefactor experiment,the degree of substitution was chosen as the index for an orthogonal experiment to optimize the sulfation conditions.The result showed that optimal technology parameters were as follows: reaction temperature 60 ℃, reaction time 13 h,the mass ratio of water-soluble dietary fiber and amino acid was 1∶3,and the ratio of amino acid and pyridine( g∶mL) was 1∶30.Through FTIR analysis,it was found that the sulfate groups were successfully grafted on the extrusion modified water-soluble dietary fiber.