Urethral bleeding after stimulation of male erection may be due to urinary tract infection, urinary stones, mechanical injury and other reasons. 1. urinary tract infection: urinary tract infection due to bacterial damage to the urethral epithelium, in the state of erectile urethral expansion, can cause urethral bleeding. 2. urinary stones: urinary stones, due to erection may make the stone and urethral mucosa friction, which may cause urethral bleeding. 3. Mechanical injury: erectile situation if the sexual behavior is strenuous, can cause urethral bleeding, will be mistaken for urethral bleeding. It usually manifests as transient bleeding. Urethral bleeding after erection may also be caused by other factors. Patients are advised to go to the urology department of regular hospitals for examination and treatment under the guidance of specialists, while avoiding wound infection.