Abstract: Taking purple sweet potato as the main raw material and sensory evaluation as indicators, the optimal fermentation parameters of purple sweet potato were determined by response surface method. The lyophilized powder of fermented purple sweet potato was used as one of the main raw materials with the addition of skim milk powder and inulin to make low-sugar and low-fat fermented purple potato milk tablets. The characteristic flavor substances of low-sugar and low-fat fermented purple potato milk tablets and regular low-fat purple potato milk tablets were analyzed by electronic nose. The results showed that when the fermentation time was 9.5 h, fermentation temperature was 37.6 ℃, the amount of mixed starter was 7.6%, and the ratio of material to liquid was9∶14（g/mL）, the sensory quality of lyophilized powder produced by purple sweet potato was the best. The results of electronic nose analysis showed that the flavor components of milk tablets differed greatly before and after fermentation. The volatile components of purple sweet potato milk tablets with different technical formulations were obviously different. The addition of inulin and granulated sugar had little effect on the principal component of the flavor of fermented milk tablet of purple sweet potato. The results indicated that inulin could replace sugar and be added into fermented purple sweet potato milk tablets, which could provide a new idea for the production and development of low-sugar milk tablet and deep processing of purple sweet potato.