Atomic absorption spectrophotometry and highly effective liquid phase chromatography techniques were used to detect the main component of the sweet sorghum stem juice,including sucrose,fructose and glucose content,total nitrogen and a number of metal element content;using response surface method to establish the urea,magnesium sulfate,potassium dihydrogen phosphate,calcium chloride the quadratic model of addition,and to gain the mathematic model of optimal combination.The results showed that urea,magnesium sulfate,potassium dihydrogen phosphate,calcium chloride additive amount 8.422 8,1.093 8,4.170 2,and 4.042 2 g/L respectively.So that the alcohol yield reached 93.18%,compared to before optimize fermentation the concentration of alcohol increased 9.56 g/L.