Abstract: The enzymatic saccharification conditions of fermentable sugars production were studied to utilize the Jerusalem artichoke residues( JAR) effectively.The effects of combining forms for cellulase,amylase and xylanase on enzymolysis yield were studied on the basis of components analysis,and the optimum enzymatic conditions were selected. The structural characteristics changes were studied by scanning electron microscopy( SEM) and X-diffraction( XRD). The results showed that the content of cellulose,hemicellulose,and starch were 22.54%,18.00% and 20.49%,respectively.The total carbohydrates content were reached up to 61% in JAR,which beneficial to prepare the fermentable sugar such as glucose.The results of enzymatic hydrolysis showed that the enzymolysis yield of multiple enzyme hydrolysis( cellulose,amylase and xylanase,successively) were higher than sole enzyme hydrolysis.The dosage of three enzymes was 7200 U / g,12000 U / g and 10000 U / g,respectively. The enzymolysis time of three enzymes was 3.5 h,3.5 h and 3.0 h,respectively. Under this condition,the enzymolysis yield was reached to 75.33%.The results of SEM and XRD indicated that the original compact structure of JAR was changed to porous after enzymolysis,and the ravines on surface were obvious.The relative crystallization index of sechemeⅠwas the highest and the crystal structure of cellulose was degraded sufficiently,compared with the other sechemes( Ⅱ~ Ⅶ).In conclusion,the total carbohydrates content were rich in JAR,and fermentable sugars can be obtained after enzyme composite hydrolysis,which would lay the foundation for the ethanol fermentation.