The causes of male infertility are mainly divided into two categories: 1, sexual dysfunction: 1, male erectile dysfunction: due to various reasons, the penis can not normal erection or erection does not last, can not ejaculate semen into the female reproductive tract and lead to the female party can not be conceived. 2.Male ejaculatory dysfunction: mainly includes ejaculation disorder and retrograde ejaculation disorder. Ejaculation disorder means that the penis can have normal erection and intercourse, but cannot ejaculate semen, or can ejaculate under other circumstances, but does not ejaculate in the vagina, and therefore cannot reach orgasm and obtain sexual pleasure, and can also cause male infertility. Retrograde ejaculation means that although intercourse is normal and the man can have orgasm and ejaculation, the bladder neck is open during ejaculation (the bladder neck is closed during normal ejaculation) and the semen goes through the “back door” and flows backwards into the bladder from the posterior urethra instead of ejaculating from the urethra. The diagnosis is relatively simple and can be confirmed by examining the urine after the ejaculation and finding a large number of sperm. As the “seeds” of fertility cannot be “sown”, the wife is unable to conceive. The main abnormalities of semen parameters are: oligospermia (including azoospermia), weak spermia (including dead spermia), and teratozoospermia. (a) The causes of low sperm count? 1, genetic factors: including karyotype abnormalities (47XXY (Creutzfeldt-Jakob syndrome), other 46XX, and chromosome balance translocation, Roche translocation, Y chromosome microdeletion, etc.), congenital vas deficiency, cryptorchidism, etc. 2. Reproductive tract obstruction (obstructive azoospermia): inflammatory obstruction of the epididymis, mostly secondary to bilateral hiatal hernia in early childhood, bilateral vasectomy, and ejaculatory duct obstruction. 3, endocrine factors: relatively rare, clinically common are idiopathic hypogonadotropic hypogonadism and hyperprolactinemia. (2) Causes of decreased sperm vitality? 1, genetic factors: such as cilia immobility syndrome. 2, incomplete obstruction of the ejaculatory duct; 3, varicocele; 4, infectious factors: reproductive tract infections, including urethritis, prostatitis, orchitis, epididymitis, etc. (C) the causes of the increase in sperm malformation rate? 1, genetic factors: such as round-headed spermatozoa, needle-headed spermatozoa, large-headed multi-tailed spermatozoa, short-tailed spermatozoa and other unknown causes; 2, environmental and tobacco and alcohol factors: work factors, bad habits such as smoking and alcohol, prolonged exposure to heavy metals, etc.