Abstract: The effect of adding amount of liquid whole egg,purple sweet potato powder,xylitol,color fixative,soybean oil,cake emulsifier and baking powder on comprehensive score of xylitol purple sweet potato sponge cake was studied.On the basis of the single- factor test and according to Box- Behnken design,the production formula was optimized by response surface methodology. The results showed that the optimum formula( baker's percent) of the product was pastry powder 100%,liquid whole egg 157%,purple sweet potato powder 25%,xylitol58%,sugar 42%,color fixative 0.8%( citric acid 0.4% and ascorbic acid 0.4%). It was not necessary to add soybean oil,cake emulsifier and baking powder.The comprehensive score of product in verification test was 92 ±0.5,which was basically consistent with the theoretical value( 92.39).