With cotton seed hull as raw material, the influence was studied about the enzymatic properties and microstructure of cottonseed hull by four pretreatment methods of the dilute acid, acid pretreatment after alkali, alkali and alkaline H₂O₂. The results showed that the lignin content of cotton seed hull by the pretreatment method of alkaline H₂O₂ was decreased by 67.5%; the rate of xylan extraction about enzymatic hydrolysis for 12 hours was 21.4%; and more Xylobiose was obtained; at the same time, the microscopic structure appeared clear and loose.