The cause of enlarged prostate in the elderly who cannot urinate is the proliferation of prostate tissue caused by factors such as increasing age and androgen action, which presses on the urethra and causes urethral stricture. Although the specific etiology of prostatic hyperplasia and hypertrophy is still not clear, it is recognized that increasing age and androgen action are two important factors in the development of this disease. The incidence of this disease gradually increases with age, and men over 45 years old have different degrees of morbidity; androgen action and prostate epithelial cell hyperplasia are closely related to the patients with this disease in the removal of testicles after the prostate gland to varying degrees of atrophy. As the urethra through the prostate, prostate gland hyperplasia hypertrophy protrudes into the posterior urethra, resulting in the prostate part of the urethra pressure, bending, elongation, urethral stenosis and increased urinary resistance, so it will be unable to urinate.