The pain in the back of the penis may be caused by urinary system infection, inflammation and external injury, it is best to go to the regular hospital for blood and urine routine. 1. urinary tract infection: urinary tract infection including urethritis, cystitis, etc., will mostly appear the symptoms of urinary pain, mainly caused by bacterial infection. 2. Prostatitis: sedentary, alcoholism or unclean sexual intercourse bacteria retrograde, etc., leading to urinary urgency, painful urination, increased urethral discharge problems. 3. external injury: external impact or sexual process caused by the injury, you can go to the hospital to improve the ultrasound examination, to clarify the degree of damage, and then take the treatment program. If the pain intensifies without relief, please go to the hospital in time to avoid delaying the aggravation of the condition.