Abstract: The aim of this study was to treat purple sweet potato by microwave combined with high pressure to improve its antioxidant capacity and inhibit the occurrence of the browning reaction. Then, the modified purple sweet potato was used as raw materials for the development of biscuits, and the processing recipe was optimized by the orthogonal test and fuzzy mathematics comprehensive evaluation method. Anthocyanin content and polyphenol oxidase (PPO) activity in purple sweet potato were used as indicators, the optimal conditions of microwave combined high pressure treatment determined by a single factor test were microwave power 450 W, microwave time 20 min, high-pressure temperature 115 ℃, and high-pressure time 40 min, and the anthocyanin content increased by 2.56-fold and polyphenol oxidase activity decreased by 45.71% under the optimal conditions compared to the native purple sweet potato, respectively. Furthermore, sensory evaluation was used as indicator, the best processing recipe of modified purple sweet potato-based biscuits was low-gluten flour 40 g, modified purple sweet potato powder 60 g, white granulated sugar 45 g, butter 75 g, egg 60 g, and edible salt 1 g optimized by orthogonal optimization and fuzzy mathematics comprehensive evaluation method. The prepared modified purple sweet potato-based biscuits had uniform color, complete appearance, crisp taste and the flavor of purple sweet potato.