In brief, the causes of infertility include: congenital developmental abnormalities, hereditary diseases, abnormal semen, inability of sperm to enter the vagina, reproductive system infection, vas deferens obstruction, varicocele, sperm production disorder, cilia immobility syndrome, psycho-spiritual factors, bad lifestyle habits, etc. If the testes are the boundary can be divided into the following three major categories of causes: I. Pre-testicular causes 1. Diseases of the hypothalamus and pituitary gland. Including primary gonadotropin reduction hypogonadism and secondary gonadotropin and testosterone are low in two kinds of diseases, the former most onset in prepubertal, manifested as small and soft testes, lack of male secondary sexual characteristics; the latter mostly occurs after puberty, patients with normal male sexual characteristics but have testicular atrophy and varying degrees of sexual dysfunction. 2. Excessive estrogen or androgen in the body. Such as cirrhosis of the liver, adrenal or testicular tumors and other diseases of the impact. 3, hyperadrenocorticism, or overdose of hormonal drugs resulting in the decline or cessation of testicular spermatogenic function. 4, other endocrine diseases. Such as hypothyroidism, hyperthyroidism, diabetes, etc. on the spermatogenic function must also affect. Second, the testicles themselves cause 1, environmental factors. Such as testicles affected by long time high temperature, surrounding radioactive substances, chemical toxic substances, long time to take certain drugs, etc. 2, inflammation or injury of the testes themselves. 3, congenital defects, such as chromosomal abnormalities or cryptorchidism. 3. Post-testicular causes 1. Blockage of vas deferens. 2.Sperm maturation disorder in the epididymis. 3.Ancillary gonadal diseases. Such as prostatitis, etc. 4.Sexual dysfunction and external genital deformity make sperm unable to enter female vagina.