Sudden oligozoospermia over 50 years old may be caused by testicular spermatogenic dysfunction, obstruction of the reproductive tract, and too frequent sex life. 1. Testicular spermatogenic dysfunction: diseases such as orchitis and varicocele may affect the spermatogenic function of testes, which may lead to testicular spermatogenic dysfunction, resulting in oligozoospermia or even azoospermia. 2. Reproductive tract obstruction: men over 50 years old have epididymitis, seminal vesiculitis and other reproductive tract infections, and inflammation stimulation causes reproductive tract obstruction, resulting in oligospermia and azoospermia. 3. Sexual life is too frequent: men over 50 years old who have sex too often can also lead to a decrease in sperm count, resulting in oligospermia or even azoospermia. There are many reasons why a man over 50 years old may have low sperm count and no sperm, so it is recommended that the patient go to the hospital in time to have the cause clarified under the guidance of the doctor and have the treatment targeted at the cause.