Co-fermentation of stalk juice and clarified grain mash of sweet sorghum was carried out with immobilized active dry yeast in a conical flask fermenter at 30 degrees C. The results showed that co-fermentation of stalk juice and clarified grain mash can shorten fermentation time and improve ethanol efficiency compared with the control. Under the experimental conditions, the maximum ethanol concentration of 65.64 +/- 0.57 gL(-1), ethanol productivity of 5.47 +/- 0.04 gL(-1) h(-1), and ethanol yield efficiency of 89.29 +/- 0.77% were obtained from the juice with 80% volume fraction of clarified grain mash, which were 6.8, 33.5, and 13.7% higher than those of using sweet sorghum juice alone, respectively.