Mucus secretion from the lower body of 12-year-old children may be a normal phenomenon caused by the emergence of secondary sexual characteristics, or it may be caused by bacterial vaginitis, for boys also need to consider the glans caused by glansitis. 1. secondary sexual characteristics: children at the age of 12, may have begun to appear secondary sexual characteristics, there will be pubic hair, armpit hair and other phenomena, the girl may have the phenomenon of menstruation, there will also be leukorrhea, so mucus secretion in the lower body is a normal phenomenon. 2. Bacterial vaginitis: Bacterial vaginitis is caused by a combination of pathogenic bacteria such as Gardnerella. The main symptoms are increased vaginal discharge in a thin form, vulvar itching, burning sensation, and so on, and there will be odor, fever and other symptoms. 3. Glansitis: Glansitis is related to a variety of factors, including bacterial, fungal and other pathogenic infections, external material stimulation and so on. Affected children will have edema, erythema, erosion, ulceration, exudation of glans skin mucosa, etc. They will also have symptoms such as pain, irritation and itching during urination. 12-year-old children lower body secretion of mucus, there may also be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.