Abstract:Xylan，cellulose and lignin in corncob were closely linked by chemical bond.In order to extract xylan from Corncob，the combination of the pretreatment liquids and cooking methods was used.Among three kinds of pretreatment fluids（NaOH，H2SO4and distilled water），the effect of NaOH was the best.Alkaline pretreatment of corncob can make full swelling，and remove some impurities.After the alkaline pretreatment，the corncob were further cooking extraction.Orthogonal experiments were carried out for cooking conditions，The optimum extraction conditions were as follow：cooking time was 40 min，cooking temperature was 120℃and ratio of solid to liquid was 1∶10（g/mL）.Under these conditions，the extraction rate，the average degree of polymerization and color value were 26.7%，2.8 and 0.85，respectively.