Many endocrine diseases can cause male infertility, so it is necessary for infertile men to undergo endocrine tests, which are collectively called the “six sex hormones”: follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), estradiol (E2), testosterone (T) and progesterone (P). Accurate sex hormone test results can determine the location of lesions, guide clinicians for further examination and treatment, and take proven treatment plans so that treatment does not take a wrong turn. 1. Can determine the location of lesions: (1) When FSH, LH and T are significantly lower, testicular volume is small, and semen examination is of poor quality azoospermia, lesions of hypothalamus and pituitary gland should be considered. (2) When FSH is significantly increased, the small testicular volume indicates that the spermatogenic function of the testis is obviously damaged and the lesion is in the testis. (3) FSH, LH, T and other indicators are normal, testicular volume is normal, semen biochemical examination, carnitine, a glycocalyx enzyme is significantly lower, semen examination without sperm, obstructive azoospermia should be considered. 2, can determine the degree of testicular function damage: (1) When the testicular volume and FSH are in a negative relationship, LH and T are normal. Testicular volume is less than 20 ml and FSH is significantly elevated, suggesting that the spermatogenic function is seriously impaired irreversibly. (2) Increased FSH, increased LH and normal or decreased T indicate testicular failure. (3) 0T/LH ratio responds to interstitial cell function: when T/LH ratio decreases, testicular interstitial cells should be considered to have been damaged and spermatogenic function is severely impaired – oligospermia. (4) E2 increase hypermasculinity, breast enlargement, indicating testicular dysfunction. (3) Can determine which diseases are caused by: (1) Increased SH, increased LH, decreased T, increased E2, semen without sperm, and then combined with chromosome number examination, can be considered Cranfer’s syndrome. (2) Increased FSH, increased LH, increased E2 and decreased T. Combined with positive X chromosome examination, XX male syndrome can be considered. (3) Low FSH, low LH, lower than normal T and E2 in urine blood, combined with chromosomal examination and clinical, can be considered Kalman’s syndrome. (4) Low LH and low T in blood but normal FSH, combined with clinical, can be considered selective LH deficiency. (5) Normal LH, normal T, low FSH, combined with clinical, can be considered selective FSH deficiency. (6) Increased blood PRL, low FSH and low LH resulting in decreased blood T. Combined with the clinic, hyperlactatemia can be considered, and pituitary tumors cannot be excluded.