The protruding triangle below the abdomen may be caused by physiological factors such as bone development or obesity, or it may be caused by urinary retention, abdominal wall hernia and other diseases. 1. Physiological factors: the triangle below the abdomen generally refers to the pubic mound, located above the pubic bone, inverted triangle and thicker fat layer may also be the patient’s obesity and other factors, may lead to the phenomenon of the protrusion of the triangle below the abdomen. 2. urinary retention: urinary retention is mainly due to mechanical obstruction or power obstruction and other factors, the patient will have abdominal distension, urinary frequency, urinary difficulties, lower abdominal discomfort and other symptoms, which will lead to the patient has the following triangle protruding performance. 3. abdominal wall hernia: abdominal wall hernia is due to congenital factors or acquired factors, patients mainly manifested as abdominal wall mass, abdominal distension, intestinal obstruction, etc., which will lead to the phenomenon of protrusion of the lower triangle. When patients have symptoms of herniation of the lower triangle, it may be caused by physiological factors and does not require treatment. If it is caused by disease, patients should seek medical treatment in time and follow the doctor’s instructions.