Inside the navel is very smelly refers to the navel odor, the cause is divided into physiological and pathological, to pathological factors, mainly navel inflammation, umbilical nest eczema, umbilical ureteric fistula, etc., should be timely consultation, to find out the cause of the disease. 1. Physiological factors: the navel folds are rich, susceptible to environmental influences, and due to a long time do not pay attention to personal hygiene, or scratching with unclean fingers, etc., may lead to navel odor. 2. Pathological factors: (1) Umbilicitis: Umbilicitis is mainly caused by bacterial invasion of the umbilical cord stump or broken skin of the umbilical cord, early umbilicitis patients can appear red umbilical cord root, umbilical cord at the nest of the exudate symptoms, severe umbilicitis patients exudate pus, the umbilical cord center bleeding, decay, and accompanied by a foul smell, and even systemic poisoning and other manifestations. (2) Eczema of umbilical fossa: this is a kind of inflammatory dermatosis occurring in the epidermis and superficial dermis of umbilical fossa, which is mostly caused by umbilical fossa dirt, soap and water stimulation or rubbing of umbilical fossa, and the main manifestations are redness of the umbilical fossa, vesiculation, oozing, which is often accompanied by foul odor and is easy to recur. (3) Umbilical ureteric fistula: a malformation caused by incomplete atresia of the umbilical ureter during embryonic development. Clinical manifestations mainly include umbilical leakage of urine, long-term leakage of urine, which can lead to the navel pungent smell of urine, but also eczema-like changes. In addition, intra-abdominal infections, abscesses and other diseases invade the umbilical fossa depression, can also lead to the navel oozing, odor. The odor of the navel, should be timely consultation, complete the relevant examination, and the doctor for targeted treatment.