Abstract: In order to improve the physiochemical and functional properties of sweet potato dietary fiber, the sweet potato dietary fiber were treated by jet milling and instantaneous high-pressure micro fluidization method, and the composition, physicochemical and functional properties were investigated. The results showed that after treated with jet milling and instantaneous high- pressure micro fluidization method, the proximate composition changed differently, the particle size of the dietary fiber were significantly decreased, while the content of soluble dietary fiber were increased, and the physicochemical and functional properties were improved differently.In addition, the water holding capacity, oily- holding capacity, glucose absorption capacity, α- Amylase inhibitory activity, fat absorption capacity and pancreatic lipase inhibitory activity of the dietary fiber grinded by instantaneous highpressure micro fluidization method were higher than jet milling method. Therefore, these results suggested that instantaneous high-pressure micro fluidization method treated sweet potato dietary fiber has potential to be used in the field of food and health care products.