The purple sweet potato was used as raw material to make purple sweet potato raw granules by explosion puffing drying technology at modified temperature and pressure. The study includes the effects of different puffing temperature, stagnant time, vacuum drying temperature on the product color index b, content of anthocyanins and iodine blue value. By using Box-Behnken design of the response surface methodology(RSM) to determine the technical conditions as follows: puffing temperature was 80 ℃, stagnant time was 5min and vacuum drying temperature was 69 ℃. Different factors have different effects on the product, and the biggest factors are puffing temperature and vacuum drying temperature. The prepared purple sweet potato raw granules under the conditions have better color, high anthocyanins and aromas are retained.