Abstract: The juice of sweet sorghum stem with soluble sugar content of 113 g/L was used as experimental material, and the model of a second order quadratic equation for the ethanol production by immobilized saccharomyces cerevisiae from sweet sorghum stem juice was developed by response surface methodology(RSM). Effects of temperature, pH value and fermentation time on ethanol production were investigated. The optimized technological parameters were as follows: temperature 31.14℃, pH 4.53 , time 13.26 h, and under these conditions , the ethanol yield was up to 39.51 g/L. The adequacy of the model equation for predicting the optimum response values was verified effectively by the validation.