The main methods of IUI include: 1) Natural cycle: for women with normal ovulation function; 2) Pro-ovulatory cycle: mainly used for patients with ovulation disorders, unexplained infertility or other infertility factors, commonly used drugs include: clomiphene, gonadotropins, etc. The basic procedure is mainly follicle monitoring: ovulatory cycle starts with ultrasound monitoring on day 3-5 of menstruation; natural cycle starts with monitoring on day 10 of menstruation. When the diameter of the dominant follicle is <10mm, monitoring can be done every 3 days; when the diameter of the dominant follicle reaches 10-14mm, monitoring can be done every 2 days; when the diameter of the dominant follicle is >15mm, monitoring can be done once a day, along with daily monitoring of urinary LH or blood LH; when the diameter of the dominant follicle reaches 18mm or when urinary LH is strongly positive, gonadotropin should be stopped and HCG 5000-10000 units should be given. 10,000 units of HCG should be given intramuscularly. Time of surgery: 24-48 hours after HCG injection for IUI.