Post-ejaculation perineum swelling and pain is often seen in too frequent sex, genitourinary system inflammation, reproductive system tumors, stones, etc., need to further improve the examination, in order to clarify the cause of the disease. 1. Sexual life is too frequent: if the patient has sex too often, especially if the duration of sexual life is too long, it can lead to prolonged congestion of the prostate, seminal vesicles, ejaculatory ducts and other parts of the patient, and the patient can be manifested as a feeling of distension of the perineal area. 2. Inflammation of the genitourinary system: such as urethritis, prostatitis, seminal vesiculitis, testicular epididymitis, etc., the above mentioned parts are uncomfortable in themselves, and during ejaculation, there is a rhythmic contraction of muscles in the perineal area, which stimulates the inflammation part and causes distension and pain. 3. Tumor of reproductive system: especially benign and malignant tumors of epididymis, testis, prostate, etc. When they are large in size, they can compress or block the ejaculatory ducts, affecting the discharge of sperms, which can cause swelling and pain in the perineum after ejaculation. 4. Stones: mainly seen in the seminal vesicles, prostate gland and the posterior urethra and other places of the stones, in the ejaculation can cause stimulation of the stone parts, in addition to the contraction of the stones caused by the extrusion will also lead to perineal area distension and pain. After ejaculation perineum swelling pain may also be other reasons, it is recommended that the patient to go to the hospital, improve the examination, in order to clarify the cause of the disease, by professional physicians for treatment.