The anaerobic digestion fiber for producing ethanol was conducted. The effects of different temperatures and total solid concentrations of anaerobic fermentation conditions on producing ethanol characteristic of anaerobic digestion fiber were investigated. The results showed that for the anaerobic digestion fiber obtained at medium temperature and low concentration fermentation (37℃, 6%), the loss of cellulose in pretreatment process was lower, and glucose conversion was higher in enzymatic hydrolysis, 33.17%. The ethanol production could reach to 41g/kg. In order to improve the ethanol yield, the conditions of pretreatment were optimized and methods of acid and alkaline pretreatment were compared. The results showed that alkaline pretreatment was more favorable. Under the mild temperature (60℃) condition, the weight loss rate decreased to 22%~56% and the recovery rate of cellulose was more than 80% after 1%~3% of NaOH pretreatment for 6~24h. Moreover, the glucose conversion increased during enzymatic hydrolysis, and ethanol yield was significantly improved. By optimizing the pretreatment parameters, the conditions of 3% NaOH, 60℃ and 6h obtained maximum ethanol yield, 87g/kg.It effectively improved the efficiency of digested fiber for ethanol production.