A two-year-old boy with a cyst on the head of the urethra is mainly a localized accumulation of fluid, which can be caused by congenital development, inflammation and trauma. 1. congenital development: abnormal congenital development of the glands around the urethra is likely to cause local fluid accumulation, resulting in the corresponding situation. 2. Inflammation: prolonged inflammatory stimulation will lead to localized blockage of the glands, secretions can not be discharged in a timely manner, which will also cause the corresponding conditions. 3. Trauma: after trauma caused local tissue mucosal damage, in the process of repair may lead to local blockage, which further leads to fluid accumulation and cause corresponding symptoms. The appearance of cysts accompanied by localized obvious redness, swelling, pain, need to consult a doctor in time to observe, after diagnosis of the condition under the guidance of the clinician to carry out standardized treatment, to avoid delays in the condition.