A duodenum internal covering membrane is disclosed. The covering membrane is made of a biocompatible material and mainly comprises an elastic ampulla and a tubular part, wherein the ampulla is positioned in the duodenal bulb, the tubular part can extend to the jejunum, the ampulla contains a wavy or V-shaped or trapezoidal or city wall-shaped elastic ring which is continuously encircled, the elastic ring is made of a memory or non-memory biocompatible material, peaks, valleys and bent angles of the elastic ring are single-circle coil springs with outward anchor hooks, the single-circle coil springs on the lower edge are penetrated and wound with recovery threads, the upper edge of the ampulla is a wavy or V-shaped or trapezoidal or city wall-shaped elastic membrane, the elastic ring and the ampulla comply with the motion of the duodenum and the bulb as a whole, and the ampulla and the tubular part can be closed up or folded into the shape of a ball or cylinder or capsule or spindle. The single-circle coil springs have strong elasticity, weak sharp injuries and good fixation for the recovery threads attached thereon, thereby being conductive to anatomical structure and basic physiological functions of the duodenum. The covering membrane within the duodenum of the present invention can be prepared into a medical device for preventing and treating obesity and diabetes.
