In order to decline the energy consumption in pulping process and keep the crystallinity of the cellulose in pulp, eucalyptus was selected in this study. Different quantities of ethanol, formic acid and MK2 and different experimental conditions led to different contents of alpha -cellulose and different crystallinities of the cellulose. The reduction of the kappa number of the pulp resulted from the increase of the liquor-to-wood ratio. With the addition of the MK2, a small quantity of ethanol could gain lower kappa number than original. Increasing the retention time and liquor-to-wood ratio played a significant role in keeping crystallinity with the addition of MK2.