If the semen is infected, such as seminal vesiculitis or seminal frenulum infection, the semen may be smelly and may be accompanied by painful ejaculation or blood in the semen, red semen color, etc. It is recommended that ultrasound examination of the seminal vesicles and culture examination of the semen be performed to further rule out the presence of infectious diseases. 2, if there is a purulent infection of the urethra can also cause semen odor, the process of ejaculation semen mixed with purulent secretions of the urethra together with the body, so it will show the phenomenon of semen odor, it is recommended to conduct urethral secretions or urine routine examination to further rule out the existence of urethral infection. 3, male external genitalia for a long time without cleaning, local presence of more secretions, the presence of This is because the external genitalia are not clean or infected and the smell is formed, not caused by the vas deferens, seminal vesicles and other related pathologies.