The effect of washing temperature, washing stages and the cooking operation on the ethanol pulp had been investigated, and the reason for higher kappa number of the ethanol pulp was discussed. The results preliminarily showed that the dissolved lignin could re-adsorb to fiber surface by means of fiber classification technology and explained the questions found during the study. Some measures were taken to reduce the kappa number, the results had shown that there was obvious absorption in the ethanol pulping;lignin remained in the pulp could easily be dissolved and the pulp with lower kappa number could be obtained at a higher temperature; the kappa number could reduce by increasing washing time; it could enable dissolved lignin to separate out from the ethanol pulp and restrain the lignin absorption by blowing cooking liquid at high temperature.