Possible reasons for the appearance of foul-smelling sperm: First, the presence of purulent urethritis, when semen is mixed with pus in the urethra and can appear bruised and foul-smelling after discharge. And the patient is often accompanied by yellowish semen, accompanied by frequent urination, urinary urgency, pain in the urethra, and can even squeeze out yellow purulent secretions from the urethra. Bacterial culture of the secretion and semen and routine urine examination are needed to further confirm the diagnosis. Secondly, when there is seminal vesiculitis, seminal fungitis, etc., such as fungal or appear to have bacterial infection, which causes the semen to contain a large amount of pus, there will be a foul smell of semen. It is usually not accompanied by frequent urination, urinary urgency, but can be accompanied by pain during ejaculation or perineal area swelling and discomfort and other symptoms, need to carry out CT examination of the lower abdomen, and semen bacterial culture to confirm the diagnosis. The third is that if you are suffering from septic prostatitis, the prostate fluid is filled with a large number of pus cells that are mixed in with the semen, which can also have a foul taste of sperm, accompanied by abnormal urination, accompanied by yellowish or cloudy semen, accompanied by painful ejaculation, distension and discomfort in the perineal area, or accompanied by distension and discomfort in the small abdomen. It is necessary to perform prostate fluid examination, semen routine examination and ultrasound examination of the prostate to further confirm the diagnosis.