The sweet potato yoghurt fermented with sweet potato and fresh milk has the unique flavor of sweet potato. It also increases the yoghurt cellulose, vitamins and various trace elements, and reduces the fat content. It can achieve animal and plant nutrition complementation, and can also reduce production costs. A new way for sweet potato processing. 1. Preparation of Sweet Potato Pulp: Take fresh sweet potato, mildew-free lesions, and sweet potato without mechanical damage. Boil for 3 to 5 minutes at 95-100°C. Beat and spare. 2. Formula: sweet potato pulp 40%, fresh milk 60%, sucrose 6%, inoculum 4%, compound stabilizer (agar: xanthan gum: monoglyceride = 0.2%: 0.05%: 0.05%) 0.3%. 3, deployment, homogenization, sterilization, cooling: According to the formula required to join the appropriate amount of milk, sugar, composite stabilizer, with a homogenizer at 25MPa homogenized twice, at 90 °C sterilization for 15 minutes, and then quickly cooled to 40 °C. 4. Inoculation, pre-fermentation, and post-fermentation: The mixed strains of inoculated bacilli and cocci (1:1) are fermented at 40°C for 6 hours, and then placed in an environment of 0 to 5°C for 16 hours for post-fermentation. A solidified yoghurt with sweet potato and milk flavors, delicate texture, and rich nutrition.