Acetylated starches as one of the most important modified starches are widely applied in food and non-food fields.The method of acetylating starch processed by ultra high pressure could shorten reaction time and conserve energy; the properties of acetylated starches by usage of ultra high pressure may further expand applications.Corn starch was substituted with acetic anhydride at pressure range of 100 to 500 MPa for 15 min by usage of ultra high pressure technology.