Belly button has a foul smell for the following reasons: 1, the most common clinical is belly button inflammation, the belly button is the umbilical cord produced stagnation, itself will also have blood vessels such as umbilical veins, and liver have ligaments connected, the rest do not have much tissue structure, while and deep tissue is not much connection. Many ordinary people visit the belly button to accumulate a lot of dirty material, caused by unclean hygiene habits, do not do cleaning can lead to easy sweat and even sediment accumulation, the formation of some relatively large belly button dirty material, easy to accumulate cause belly button infection; 2, umbilical ureteral cyst: belongs to is a congenital malformation, cystic lesions in the belly button area, will also emit a foul smell, the need for urology surgical intervention, the Removal.