1, male factors (1) male moderate semen abnormalities (two semen analysis show abnormalities): ① sperm density <20 × 106 / ml, (the number of viable sperm after treatment ≥ 1 × 106 / m), viable sperm <50%, power <2; ② morphology of normal 10% -0%; ③ serious reduction in semen volume, the volume of ejaculate is less than 2 ml per ejaculation, so that semen can not contact the cervical opening and the cervical mucus; ④ semen Long liquefaction time or non-liquefaction; ⑤ Retrograde ejaculation, the number of active spermatozoa recovered after gradient centrifugation is ≥200000, and the power is ≥2 grade. (2) Mental/neurological factors: e.g. impotence, premature ejaculation, failure to ejaculate. (3) Anatomical abnormalities such as severe hypospadias, retrograde ejaculation that prevent sperm from entering the vagina during normal sexual intercourse. (2) Female factors Infertility in women due to abnormal secretion of cervical mucus, malformation of the reproductive tract and psychological factors leading to inability to have sexual intercourse. 3, immune factors 4, unexplained infertility: men and women by routine infertility clinical examination did not find abnormalities in line with the following conditions for unexplained infertility: (1) the actual female has a regular ovulation cycle. (2) Positive post-coital test. (3) Multiple normal semen analysis, negative immunobead test or mixed antiglobulin reaction test (MAR). (4) Normal pelvis on luminal examination: no tubal adhesions or obstruction.