Ovarian reserve function refers to the number of follicles retained in the ovaries and their ability to mature and produce high-quality follicles, reflecting a woman’s fertility potential. In recent years, with the influence of internal and external environmental factors and the postponement of women’s childbearing age, more and more women become infertile due to low ovarian reserve function. According to the literature, the prevalence of low ovarian reserve function in the population is about 10%. In addition, with the development of assisted reproductive technology, it is important to assess ovarian reserve function at an early stage in order to provide patients with reasonable advice and select appropriate treatment options. However, the assessment index of ovarian reserve function is still controversial, but most researchers believe that the prediction accuracy of a single index is low, and the combined application of multiple indexes is often preferred. Currently, the indicators commonly used in clinical assessment of ovarian reserve function: 1. Age Age is the most important indicator for assessing female fertility. The decline in fertility in older women is mainly related to the decrease in the number and quality of oocytes. As women age, the follicles in the ovaries are gradually depleted, and both the quantity and quality of follicles decline, which is often manifested as a decline in fertility. It is generally recognized that fertility potential begins to decline after the age of 35 and then decreases rapidly. Therefore, age is important in determining ovarian reserve and should be the first choice. However, the aging process of an individual is subject to the interaction of many complex factors and varies greatly, so it must be used in conjunction with other indicators. 2. Basic sex hormone tests include basic follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), testosterone (T), prolactin (PRL), and are usually performed by blood sampling on the 2nd~4th day of menstruation. Basal FSH (bFSH) increases with age, and it is usually considered that a bFSH level of less than 10 IU/L suggests normal ovarian reserve function; a bFSH level of more than 10-15 IU/L in 2 consecutive cycles indicates poor ovarian function; a bFSH value of 20-40 IU/L in 2 consecutive cycles suggests insidious ovarian failure; a bFSH value of >40 IU/L in 2 consecutive cycles suggests ovarian failure; a bFSH value of >40 IU/L in 2 consecutive cycles suggests ovarian failure; a bFSH value of >40 IU/L in 2 consecutive cycles suggests ovarian failure. 40 IU/L, suggesting ovarian failure. ② bFSH/bLH ratio in older women due to the decline in ovarian reserve function, FSH rise earlier than the rise in LH, that is, a relative decrease in LH, bFSH/bLH ratio increased, predicting a decrease in ovarian reserve, ovarian hyporesponsiveness, may be more sensitive than the bFSH, basal E2 (bE2). It is generally recognized that an FSH/LH ratio of >3 is indicative of a decrease in ovarian reserve function and responsiveness, and an increase in cycle cancellation rate. ③ bE2 levels remain normal or mildly elevated in the early stages of fertility decline, and end-stage E2 levels gradually decline with increasing age and declining ovarian function. When bE2>80 ng/L, regardless of age and FSH, it suggests excessive follicular development and decreased ovarian reserve function. bE2 levels are elevated while bFSH is normal in the early stage of markedly decreased ovarian reserve function, and if both bFSH and bE2 levels are elevated, it suggests a decrease in ovarian reserve function. If bE2 is decreased and FSH ≥40 IU/L, ovarian failure is indicated. 3.Serum anti-mullerian hormone (AMH) test AMH decreases with age and cannot be detected in pre-menopausal and menopausal period, which is a marker for predicting the ovarian reserve function; AMH can be detected at any time of the menstrual cycle, which is a marker for reflecting better ovarian reserve. Inhibin B (INH-B) INH-B is a more sensitive marker of ovarian reserve function than FSH. With age, the release of INH-B gradually decreases, which reduces the negative feedback regulation of FSH release, leading to a gradual increase in FSH, and INH-B is negatively correlated with FSH. The number of sinus follicles (AFC) is the number of small follicles <10 mm in diameter detected by vaginal ultrasound. AFC is negatively correlated with age, and the accuracy of evaluation is higher in the early follicular stage; currently, AFC<5 is used as a criterion to predict the decrease of ovarian reserve. The size of the ovary is related to the number of sinus follicles in the ovary, and the ovarian reserve function decreases when the size of the ovary decreases significantly. Peak systolic blood flow velocity (PSV) of the ovarian stroma: a low PSV indicates a decrease in ovarian reserve function. The ovarian stromal blood flow velocity may be related to the gonadotropins (Gn) transported to the target cells that stimulate follicular growth. Follicular quality can be assessed to some extent by ultrasound monitoring and preovulatory hormone testing. Transvaginal ultrasonography has become an important means of monitoring follicular development and ovulation by observing not only the number of follicles in the observed ovary, but also the characteristics of follicular growth, maturation and ovulation directly. Follicle monitoring is usually performed from around the 10th day of menstruation. The doctor will record the size and number of follicles, as well as observe indicators such as follicle boundaries, tension, and translucency, and guide the timing of the next follow-up visit based on the results, thus achieving the purpose of continuous monitoring of follicle growth and development. The ultrasound performance of the normal ovulation type was mainly that the follicles before ovulation were ≥18 mm in diameter with good tension, and the corresponding dominant follicles appeared in the 9th to 12th day of the menstrual cycle, with a daily growth rate of 2 to 3 mm. The follicle disappears or collapses between the 3rd and 16th day, and a small amount of fluid dark area may be present in the patient's uterorectal fossa. In addition to normal ovulation, there are sometimes abnormalities such as small follicle ovulation, delayed follicular development, and failure to rupture luteinized follicles, which ultrasound monitoring can help to detect and intervene in a timely manner. If ultrasound monitoring of mature follicles, can also be combined with blood hormone and urine LH values to assess the quality of follicles, urine LH test paper is about to be strong positive or has been strong indicates that ovulation is imminent, generally E2 ≥ 250pg / ml, indicating that the quality of follicles is OK, with the ability to conceive. Observation of follicular development in the ovary, combined with urine LH or blood hormone tests, can accurately predict the day of ovulation, and can detect abnormal follicular development in time and intervene accordingly, and at the same time, guide the timing of coitus for women preparing for pregnancy to improve the chances of implantation. In conclusion, there are many ways to assess ovarian reserve function and follicular quality, however, they are not absolute, therefore, clinical application should be combined with the patient's condition and laboratory technology level of comprehensive consideration, choose the appropriate way, a variety of means of joint application is appropriate.