The lateral abdominal wall mass with fixed pressure pain is the main clinical sign of a semilunar hernia. The anatomical structure can be divided into 3 layers: layer 1 is the inward extension of the external oblique abdominal muscle, which fuses with the anterior rectus abdominis sheath in the middle of the rectus abdominis muscle; layer 2 is the tendon membrane of the internal oblique abdominal muscle, which is the thickest and constitutes the main body of the semilunar line and participates in the anterior and posterior rectus abdominis sheath above the semicircular line; layer 3 is the tendon membrane of the transverse abdominal muscle that migrates inward to constitute the posterior rectus abdominis sheath. In the area where the tendon membrane migrates to the anterior and posterior sheaths of the rectus abdominis muscle, a defect or gap is formed for some reason, and the peritoneum and viscera may prolapse and form a hernia. The main causes of this disease are as follows. 1, abdominal wall tissue inflammation, abscess, or after surgery, local tissue degeneration to form a weak area. 2, direct trauma. 3, nerve injury so that the local tissues lose nerve support and the ability to resist abdominal pressure is reduced.