Abstract: The mechanism of kidney deficiency and blood stasis in gynecological diseases is due to the dysfunction of the kidney, which is the master of reproduction, and the dysfunction of the reproductive axis of the kidney, tiankui, zongren and uterus, resulting in the imbalance of yin and yang, qi and blood. It is consistent with the basic pathology of kidney deficiency and blood stasis. The use of tonifying the kidney and invigorating blood as the basic method of TCM treatment for PCOS has been clinically validated. In the past 20 years, in the field of geriatric internal medicine, the essence of kidney deficiency and blood stasis has been extensively and thoroughly studied by Chinese and Western medicine. In recent years, in the field of Chinese gynecology, the relationship between kidney deficiency and blood stasis and female diseases has also received increasing attention. Polycystic ovary syndrome is a disease that is considered to be closely related to this pathology. 1. The pathogenesis of kidney deficiency and blood stasis in gynecological diseases: The mechanism of kidney deficiency and blood stasis in internal medicine is mainly due to the human body entering old age, the gradual decline of visceral functions, the gradual weakening of kidney qi, imbalance of yin and yang, or the long-term exhaustion of chronic diseases, the poor must have kidney, the biochemical function of kidney is insufficient, so that the veins and channels are withered and the blood does not flow smoothly, resulting in stasis of veins and channels. It can be considered that the kidney deficiency and blood stasis occur on the basis of systemic hypofunction and disorder, and the lesions of kidney deficiency and blood stasis are mostly systemic, such as arteriosclerosis, hypertension, diabetes, various geriatric diseases and coronary heart disease. The mechanism of kidney deficiency and blood stasis in gynecology is not exactly the same as that in internal medicine. The normal function of female reproduction is mainly related to the function of the kidney in charge of reproduction. If kidney qi is insufficient, kidney essence cannot be transformed into blood, and the blood vessels are not filled with blood and blood deficiency and blood stasis. Insufficient kidney yang will not be able to warm the blood vessels, and the blood will be cold and stagnant, or kidney yin will be deficient, and deficiency heat will be generated within the blood, injuring the fluid and burning the blood, and the blood will be thick and stagnant. Therefore, kidney deficiency can cause stasis. The stasis obstructs the vasculature and hinders the biochemistry of kidney qi, the stimulation of kidney yang and the nourishment of kidney yin, thus aggravating kidney deficiency. The deficiency causes stasis and the deficiency is compounded by the stasis, forming a vicious circle of mutual causation. If the kidney is deficient, the rushing is not full, and if the blood is stagnant, the rushing is not smooth, and the qi and blood cannot go down smoothly, and the uterus, the uterine veins and the uterine loops are not nourished. This leads to a series of gynecological diseases, such as menstruation, banding, fetus and delivery. Therefore, in gynecology, kidney deficiency and blood stasis are mainly reflected in the malfunction of the kidney-hypophyseal-uterine reproductive axis, but not necessarily in the systemic kidney deficiency and blood stasis symptoms. 2. The pathological basis of kidney deficiency and blood stasis in polycystic ovary syndrome (PCOS): the main clinical manifestations of PCOS are late menstruation, amenorrhea, infertility, ovarian enlargement and other reproductive dysfunction and symptoms of metabolic abnormalities such as obesity, acne and hirsutism. The development and maturation of the ovum is closely related to the abundance of kidney essence, and the normal discharge of the ovum depends on the stimulation of kidney yang to regulate the Qi and blood. The deficiency of kidney essence makes it difficult for the egg to develop and mature; the deficiency of kidney yang does not encourage the biochemistry and growth of kidney yin, but also stagnates the Qi and blood in the Qi and blood vessels, making ovulation lack the driving force. Therefore, kidney deficiency is the root cause of ovulation disorder. Kidney deficiency further leads to malfunction of yin and yang and qi and blood, which leads to internal stagnation of water and dampness, phlegm and dampness, which obstructs the Qi and blood vessels and stagnates the y, making it difficult to expel the eggs and enlarging the ovaries. On the basis of this, there are often more complex malfunctions of the internal organs and metabolic disorders, such as the accumulation of deficiency fire and phlegm-dampness, or dampness trapped in the spleen and kidneys, abnormal transportation and metabolic rate, resulting in obesity; or liver depression and fire, resulting in acne, hairy, etc. In other words, kidney deficiency and blood stasis represents a major or basic pathological mechanism of PCOS, but cannot encompass all the pathological states in its pathogenesis. The modern pathological basis of PCOS is related to kidney deficiency and blood stasis: Modern research has clarified that one of the main pathological features of PCOS is the elevated level of luteinizing hormone (LH) and LH/FSH ratio secreted by the pituitary gland. On the other hand, LH induces excessive androgen secretion by follicular membrane cells, which leads to follicular maturation arrest and atresia due to hyperandrogenemia. It has been demonstrated by ultrasound that ovarian volume, total area and medullary area are significantly larger in PCOS patients than in those with normal and multiple follicles. Recent studies suggest that insulin resistance (IR) is a central part of the pathophysiology of PCOS, and that IR directly stimulates ovarian androgen synthesis, increases pituitary LH release, and exacerbates the pathology of PCOS. Fibrinolytic enzyme (tPA) is produced by activation of fibrinolytic plasminogen and is expressed locally in the follicle, which plays an important role in blood clot lysis and follicular wall rupture for ovulation, while PAI-1 is its inhibitor. In PCOS patients, fibrinolysinogen is significantly higher in the ovarian stroma than in the cortex, and it is higher in those who have not ovulated for ≥10 years than in those who have not ovulated for ≤10 years, and it is more pronounced in the ovarian cortex of obese patients. These pathological mechanisms in PCOS, at the ovarian level, may prevent follicular rupture without ovulation and, over time, may lead to an increased risk of cardiovascular disease systemically. The clinical symptoms caused by this female reproductive endocrine and ovarian local lesions are consistent with those caused by the malfunction of the kidney in Chinese medicine, especially the lesions of follicular atresia, interstitial hyperplasia and ovarian enlargement can be considered as blood stasis further caused on the basis of kidney deficiency. 4, tonifying the kidney and activating the blood is the basic method of TCM treatment for PCOS: kidney tonifying herbs are believed to have endocrine hormone-like effects, which can have a two-way regulation effect on the female gonadal axis. Since Lin Zhijun founded tonifying the kidney – invigorating blood circulation – tonifying the kidney – invigorating blood circulation to regulate menstruation as an artificial cycle of Chinese medicine for the treatment of PCOS, clinical studies following this idea of using tonifying the kidney and invigorating blood to treat PCOS have been widely carried out with certain efficacy. The pathological essence of kidney deficiency and blood stasis in PCOS was further confirmed.