Lignocellulosic biomass is one of the largest carbohydrate sources and has huge potential for biofuels production. However, the problem with lignocellulosic feedstock is that it has useful sugars locked in by lignin, hemicellulose, and cellulose. Some kind of pretreatment; therefore is needed to make carbohydrate accessible which later can be fermented to produce ethanol. The results from this research indicated that the yields of glucan (93%) and xylan (82.8%) were improved by using milling combined with ELLA pretreatment. The optimal enzymatic hydrolysis efficiencies were obtained under 10 min for ball milling time, pretreatment at 1 h, temperature at 150°C, S/L = 0.5 and ammonia loading at 0.25 g-NH3/g-biomass. This method reduced the pretreatment time and short milling time and thus has potential of reducing the energy consumption and promising the application in the large scale. Keywords: corn stover, milling pretreatments, ammonia pretreatment, bioethanol.