Abstract: The effect of steaming, baking and frying on the soluble sugar content and moisture of sweet potato was investigated.In baking and cooking processing, the soluble sugar content of sweet potato first increased, then decreased, and rose again in processing end-stage.Being steamed, the content of soluble sugar in sweet potato increased first and then reduced. While the content of soluble sugar declined in fried process. Steaming, boiling, and roast didn't make great impact on the moisture content in sweet potato.But in fried process, moisture content of sweet potato continued to decrease as the heating time increased. The influence of extraction about temperature, time, and Liquid ratio on the extraction amount of soluble sugar was discussed by single factor and orthogonal test method.The results showed that under the condition of the steamed for 24min, liquid ratio made the greatest impact on the extraction of soluble sugar, followed by the temperature, and time was the last.The optimum technological conditions in which water soluble sugar extracted were liquid ratio 1g∶200mL, extraction time of 20min and the extraction temperature of 40℃, and the extraction rate is 41.03%.When being baked for 40min, liquid ratio also made the greatest impact on the extraction of soluble sugar, then the temperature, and last was the time.The optimum technological conditions were liquid ratio 1g ∶ 250mL, extraction time of 30min and the extraction temperature of 50℃, and the extraction rate is 51.31%.