Patients with PCOS who have fertility requirements mostly need ovulation treatment in order to get pregnant, and pharmacological ovulation treatment for PCOS has made great progress in the last 50 years, but some patients have poor outcomes with conventional methods, so choosing the right regimen is the key to ovulation treatment. (1) Clomiphene (CC): The use of clomiphene for ovulation treatment was reported by Greenblatt in 1961, and CC has become the drug of choice for ovulation treatment in PCOS. CC binds to the hypothalamic estrogen receptors, blocking the central nervous system’s sensing of circulating estrogen levels and increasing the secretion of pulsatile GnRH and gonadotropins, further causing follicular growth and development. further causing follicular growth and development. In addition, CC can also directly affect the pituitary and ovary by increasing gonadotropin secretion and synergistically enhancing FSH-induced aromatase activity, respectively.CC can also exhibit anti-estrogenic features in other parts of the female reproductive tract, particularly the endometrium and cervix (causing cervical mucus to thicken). These anti-estrogenic effects have a negative impact on pregnancy. Treatment is often started after the onset of menstruation in the natural cycle or after progestogen withdrawal bleeding, i.e. from days 2-5 of the cycle, with 5 days of dosing. The timing of initiation does not significantly affect ovulation rates, pregnancy rates and endometrium, and starting early in the follicular phase ensures adequate follicular recruitment. The starting dose of clomiphene is usually 50 mg, while 100 mg is more appropriate for obese women. If there is no ovulatory response by these methods, the next dose can be increased by 50 mg until ovulation occurs. Although the FDA recommends a maximum daily dose of up to 250 mg, the highest dose commonly used clinically is 150 mg. The smallest possible dose should be used for treatment, as higher doses do not improve pregnancy outcomes and theoretically have a negative effect on endometrial thickness and implantation. If the maturation of follicles is monitored by ultrasound, the dominant follicle is considered mature when it reaches an average diameter of 18-20 mm. The pregnancy rate is 30-60% with CC alone. The two most significant side effects with clomiphene are mild ovarian enlargement (13.6%) and multiple pregnancies. Other side effects include hot flashes (10.4%), abdominal distention (5.5%), and rarely visual disturbances (1.5%). Some patients are ineffective with CC treatment, called clomiphenecitrate resistance, but the current definition of clomiphenecitrate resistance varies, with maximum doses ranging from 150-250 mg, applied for 3 consecutive cycles, all without ovulatory response. (2) Gonadotropin (Gn) For patients with CC resistance, gonadotropin (Gn) is the commonly used ovulation-promoting drug, including FSH and HMG. There are various preparations of Gn, such as hMG, urinary FSH and recombinant FSH, but all of them have high price, multiple pregnancy and ovarian hyperstimulation syndrome when applied ( The risk of ovarianhyperstimulation syndrome (OHSS) is a concern. The conventional method of starting on 3-5 days of menstruation with 1 HMG/d or 75 IU/d of pure FSH per day has a higher ovulation rate and a higher pregnancy rate, but a high incidence of ovarian transitional stimulation syndrome (OHSS) and a high rate of multiple pregnancies. At present, most of them use small dose slow increase regimen that is started on the 3rd day of menstruation, 1 stick, once every other day, if the ovaries do not respond, increase half stick every 7~14 days, i.e. 37.5 IU, until the dominant follicle is seen under ultrasound, increase to 225 IU/d. The ovulation rate of this method is 70~90%, single follicle development 50~70%, cycle pregnancy rate 10~20%, the incidence of OHSS is lower about 0 ~5%, but the treatment cycle is long and the patient cost is relatively high. (3) Letrozole: Ovulation-promoting therapy is a new indication for aromatase inhibitors (AIs), which were previously used mainly in the treatment of breast cancer. They can be applied alone or in combination with FSH. Major side effects include gastrointestinal reactions, fatigue, hot flashes, and head and back pain. The aromatase inhibitor class of drugs currently in clinical use is letrozole, mainly used in clomiphene-resistant patients with an ovulation rate of 80%, mostly applied after the start of the menstrual cycle or after progesterone withdrawal bleeding, on days 3-7 of menstruation (5 days in total), 2.5-5.0 mg/day, followed by the same monitoring process as clomiphene. Insulin-sensitizing drugs (ISD) therapy: A major feature of PCOS is insulin resistance, leading to compensatory hyperinsulinemia in order to maintain normal glucose tolerance (normal response of insulin after glucose intake). In young women with PCOS, hyperinsulinemia is a major risk factor for abnormal glucose tolerance and later cardiac disorders. In addition, hyperinsulinemia can cause an increase in ovarian androgen synthesis, which can lead to anovulation, amenorrhea and infertility. Many women with PCOS are obese, and insulin resistance is more pronounced due to weight gain; non-obese women with PCOS (20-50% of PCOS) tend to have increased waist/hip ratios and more pronounced insulin resistance than the normal group. The main insulin-sensitizing drugs are metformin, troglitazone, rosiglitazone, ioglitazone, and D-Chiro-Inosito, and their main indications are women with PCOS who have insulin resistance, impaired glucose tolerance, or type 2 diabetes. Metformin is commonly administered as 500 mg/dose orally three times daily for 2-3 months.