Male infertility symptoms are the result of many diseases or factors, usually divided into pre-testicular, testicular and post-testicular segments depending on the disease and factors interfering or affecting the fertility segment, but there are still a large number of patients for whom no cause can be found (clinically known as idiopathic male infertility). 1, pre-testicular factors Mostly endocrine causes of male infertility, the impairment of reproductive function in these patients is secondary to the imbalance of hormones in the body. In fact, the production and maturation of normal sperm is dependent on a relatively balanced endocrine system in which various hormones work in harmony to maintain male secondary sexual characteristics as well as reproductive functions. In other words, although men don’t have a period, endocrine disorders in men can also have serious consequences. There is a very important axis that maintains the normal physiological cycle and reproductive function in women, the hypothalamus-pituitary-gonadal axis, in fact, this axis is also in the male body to maintain the normal physiological function of men, but the gonads in men are not the ovaries but the testes. Therefore, either hypothalamic or pituitary disorders, or endogenous or exogenous hormonal abnormalities can cause disorders of this axis, which can lead to male infertility. Most commonly, excessive obesity and liver insufficiency may cause an increase in estrogen and an imbalance in the estrogen/androgen ratio, resulting in male infertility, and hyperthyroidism or hypothyroidism may also alter hypothalamic hormone production and the estrogen/androgen ratio, resulting in male infertility. Excessive glucocorticoids can suppress LH secretion, which can also lead to impaired spermatogenesis and maturation. Some pituitary tumors may cause hyperprolactinemia: excessive prolactin can cause a decrease in FSH, LH and testosterone, leading to loss of libido, overflow of breast milk, male breast enlargement and spermatogenic disorders. 2, testicular sex factors testes as male gonads, and women’s ovaries as important, if the testes abnormalities lead to its function is reduced or even completely lost, for men, fertility is very difficult. First of all, some congenital abnormalities can lead to poor testicular function, for example, some chromosomal or genetic congenital abnormalities, such as Crohn’s syndrome, sexual inversion syndrome, XYY syndrome and other chromosomal or genetic abnormalities can lead to male infertility. Secondly, harmful external environment can also cause damage to the fragile testicles, such as radiation, certain drugs, food and special work environment factors. Mechanical factors are also a direct blow to the testicles, such as testicular trauma and surgery, testicular torsion, etc., which directly affect the function of the testicles, thus affecting male fertility. A special type of factor is the immune factor, under normal circumstances there is a barrier between sperm and blood, the male body will not produce antibodies to sperm, but once the infection and other factors that cause the male reproductive tract immune barrier is destroyed, sperm, sperm plasma will be considered as foreign invaders, in the body to produce anti-sperm antibodies, sperm plasma will agglutinate, can not cross the cervical mucus, will also lead to male infertility . 3, post-testicular factors If the previous two major factor abnormalities can be ruled out, the superior orders can be given, the testicular factory can be produced, then the next big challenge is transportation. Obstruction of the vas deferens, disorders of sperm function and movement, and disorders of intercourse and ejaculation can all cause male infertility. 4, idiopathic causes In addition, there are still many male infertility cases where the exact cause cannot be found, and the specific cause may involve one or more of the above. With the progress of science and technology, perhaps we can uncover more causes.