The objective was to investigate the effect of pretreatment methods on the characteristic of purple potato by explosion puffing drying. The effects were analyzed, from the slice thickness, concentration of citric acid solution, blanching time, freeze-thaw treatment and pre-drying time on moisture content, color difference, hardness, rehydration ratio and apparent density of explosion puffing drying purple potato. Results showed that the appropriate pretreatment conditions were as followed: slice thickness of 2 mm, color protection time by 0.2% citric acid solution for 20 min, water boiled at 100 ℃ for 1 min, freezing at -18 ℃ for 12 h. At room temperature of 20 ℃ for natural thawing, puffing purple potato was prepared at the puffing conditions at puffing temperature 80~90 ℃, the vacuum drying temperature of 60~70 ℃. At this puffing condition, the dehydration purple potato was of good color, crispness and taste which had the moisture content of 4.04%, hardness of 327.28 g, △E of 33. 21, rehydration ratio of 3.85, apparent density of 0.76 g/mL, and anthocyanin content of 291.60 mg/100 g(dry content).Results showed that the combination pretreatment of color protection, blanching and freeze-thaw can significantly improve the quality of purple potato puffed products.