To effectively improve the enzymatic hydrolysis rate of carbohydrates in lignocelluloses, the liquid ammonia treatment (LAT) was employed as pretreatment for Miscanthus floridulus. The pretreatment temperature T, Miscanthus floridulus moisture M, residence time t and the ratio of ammonia to biomass (dry basis) k were chosen as variable factors. In the experimental ranges of T (70~170 ℃), M (20%~200%), t (5~30min) and k (0.5~5.0), the influences of different variable factors on enzymatic hydrolysis of Miscanthus floridulus were investigated. The chemical composition analysis showed that the chemical constitution of Miscanthus floridulus was close to Saccharum arundinaceum and Miscanthus sinensis, and it could be a prior species of plant energy. The pretreatment methods and effects of these biomasses could be used as reference for each other. The parameter optimization results show that the optimal LAT pretreatment conditions for Miscanthus floridulus were 130℃, 80% moisture content, 10min residence time and 2.0 ammonia to biomass ratio. Enzymatic hydrolysis using cocktail enzymes including cellulase, βglucosidase and xylanase for 72h after pretreatment under optimal conditions, the glucan and xylan hydrolysis rates of LATtreated Miscanthus floridulus achieved 72.1% and 82.5%, which were 3.3fold and 4.3fold than those of untreated biomass respectively. The total fermentable monosaccharides after pretreatment under optimal conditions following enzymatic hydrolysis was 55.8g per 100g of dry raw material. Compared with untreated substrates, it was about 3.65fold in sugar yield for LATtreated substrates. As a result, the LAT process significantly reduced the recalcitrance of Miscanthus floridulus and facilitated biomass conversion to fermentable sugars.