Abstract: Confirm parameter optimization of extraction process of anthocyanins from purple aweet potato. Some factors affecting the ratio of extraction of proanthocyanidins such as extraction concentration, extraction temperature, extraction time and ratio of material to liquid were respectively studied used citric acid as extractant, the preparation process of anthocyanins from purple sweet potato was optimized according to Box-Behnken central composition design principle on foundation of single factor experiment, the method of response surface methodology (RSM) with 3 factors and 3 levels combined with Design-Expert data analysis software was adopted with the extraction yield of anthocyanins from purple sweet potato as the absorbance. The anthocyanins extraction yield would respectively reach the maximum when some parameters as follows:extraction concentration was 5%, extraction temperature was 50℃, extraction time was 4h, ratio of material to liquid was 1∶20g/mL, and RSM also confirmed that affecting the ratio of extraction of proanthocyanidins in turns as follows:ratio of material to liquid, extraction temperature and extraction time. The optimum preparation conditions were obtained as follows:extraction temperature 46℃, extraction time 6h, ratio of material to liquid 1∶23g/mL. The anthocyanin extraction amount was 159mg/100 g under these condition.