Belly bump below the navel may be caused by tumor, feces, flatulence or pregnancy. 1. Tumor: If there is an active tumor in the abdomen, it will produce a movable hard lump, such as ovarian tumor or lipoma, which is often painless when pressed, resulting in a small abdominal bulge below the belly button. Tumor treatment should be considered in conjunction with the actual situation of surgical resection. 2. Feces: patients with long-term constipation have feces stagnation in the intestinal tract, which leads to the appearance of movable hard lumps, resulting in abdominal protrusion below the navel. Patients can be relieved after defecation, and patients should pay attention to drinking more hot water to promote intestinal peristalsis. 3. Flatulence: localized cold, emotional fluctuations or strenuous exercise may lead to gastrointestinal dysfunction, resulting in undigested and absorbed food residue retained in the gastrointestinal tract fermentation, gas production increased, resulting in patients with belly button below the belly bulge. 4. Pregnancy: With the increase of pregnancy, there is a gradual bulging of the abdomen below the navel. Excluding physiological factors, if the lower abdomen bulge progressive aggravation, need to go to the hospital in time.