The causes of azoospermia include many aspects, congenital and acquired, endocrine, testicular itself and obstructive, etc. The following are some of the most common clinical azoospermia. The following are some of the most common clinical azoospermia: 1, Kirschner’s Syndrome: this kind of azoospermia patients are often manifested as scanty beard, laryngeal knot is not obvious and even more delicate skin and other male secondary sexual characteristics are not obvious or feminized signs, bilateral testes such as peanut-like size of young children, sex hormone test suggests that spermatogenic dysfunction of the testes and androgen decline, the culprit lies in the genetic chromosome abnormality, which has one more female chromosome than normal males. The culprit is a genetic chromosome abnormality, which has one more female chromosome than normal males. In terms of treatment, we can try microscopic testicular sperm retrieval, and it is reported that the success rate of sperm retrieval can be up to 20 to 30%, in addition, we can also choose sperm supply for assisted reproduction or adoption of children. 2. Micro-deletion of Y chromosome: There are genes on the Y chromosome of men that are closely related to spermatogenesis, and if this gene is missing, it can lead to spermatogenesis dysfunction of different degrees. 3. No spermatozoa after testicular inflammation: men who have suffered from testicular inflammatory diseases, due to the lack of timely treatment or incomplete treatment at that time, the testicles gradually atrophy, and ultimately lose the ability to produce sperm completely. In this case, microscopic sperm retrieval can also be attempted, and the rate of successful sperm retrieval is higher than that of Kirschner’s syndrome. 4. Obstructive azoospermia: It is the most common type of azoospermia with the highest incidence rate and the most common in clinic. Various reasons lead to the blockage of the vas deferens, which can exist in any one or more places in the testis, epididymis, vas deferens or ejaculatory ducts, and the cause of the obstruction may be the narrowing of the inflammation, the injury of seminal tracts, the vas deferens after vasectomy, or congenital dysplasia or absence of the vas deferens, and so on. Possible factors leading to azoospermia also include environmental toxins, radiotherapy, endocrine abnormalities, and many others. In short, in the case of azoospermia, striving to find the etiology of its source is the key, as well as the prerequisite and basis for treatment. The same also includes the common low, weak and abnormal spermatozoa above the moderate level, should try to seek the cause first, and subsequent targeted treatment may be more effective.