The purple sweet potato wine processing technology was optimized by single-factor experiment and orthogonal experiment with alcohol content, sensory evaluation, pH value and sugar content as the indicators, wheat koji and Saccharomyces cerevisiae S45 bred from plasma mutagenesis as additive. The results showed that the optimum fermentation conditions were: fermentation temperature 25℃ for 7 days, addition amount of wheat koji 3%, and addition amount of Saccharomyces cerevisiae 3% which was added immediately. The alcohol content of the purple sweet potato sake was 11.3%(v/v), total suger content 3.55g/L, solids content 4.3g/L, pH 3.34, total acid 3.90g/L. The research on community succession in the process of fermentation showed that bacteria bred earlier than the other fungoid, and the quantity increased quickly at first then slow down rapidly. Next was mould then the yeast. After fermentation for 7d, compared with the initial fermentation the quantity of yeast kept the same, while those of bacteria and mould decreased significantly.