Use of Trichoderma reesei RT-P1 crude enzyme powder and of this powder with 10% v/v Saccharomyces cerevisiae for ethanol fermentation of sweet sorghum fresh stalks were investigated. The optimal conditions were determined by orthogonal experiment method. With T. reesei crude enzyme powder, the optimal condition for the Keller cultivar was at 25 g with 4 g enzyme loading and for the Cowley cultivar at 30 g with 5 g enzyme loading, both with 8 days fermentation at pH 5 and 30 degrees C. At the optimal conditions above, ethanol concentration, productivity and yield of the Cowley cultivar (35.00 g/L, 0.18 g/L h and 0.38 g ethanol/g substrate, respectively) were higher than those of the Keller cultivar (20.46 g/L, 0.11 g/L h and 0.28 g ethanol/g substrate). The addition of 10% v/v S. cerevisiae to fermentation at the optimal conditions showed no significant variations in ethanol concentration, productivity and yield for both cultivars. (C) 2011 Elsevier Ltd. All rights reserved.