When the follicle volume reaches 21×18mm, it usually means that the follicle has developed and matured, at this time, the injection of chorionic gonadotropin, usually in 32-36h, ovulation can occur. Chorionic gonadotropin refers to injectable chorionic gonadotropin, the main components of which are chorionic gonadotropin, human albumin, low molecular dextrose and so on, which belongs to the gonadotropin drugs, and it can maintain the function of luteal body of a woman, so that the corpus luteum can synthesize progesterone, and promote follicle production, maturation and discharge. Generally speaking, a woman can only produce one dominant follicle each month, while ovulation promotion is the use of artificial cycle to promote the body to produce multiple dominant follicles. After the injection of chorionic villus, the follicular fluid will increase, the follicular cavity, the follicle size will increase significantly, the diameter of the follicle can be up to 18-23mm, then chorionic villus can mimic the peak of luteinizing hormone, which can promote ovulation, so that at 32-36h, ovulation can occur. After injection of chorionic villus promotion, the body’s condition should be closely observed during the process of ovulation promotion, because chorionic villus promotion can induce mild to moderate ovarian enlargement, accompanied by mild gastric distension, gastric pain, pelvic pain and other symptoms, which can usually subside within 2-3 weeks, but some people may cause a large amount of body fluids to accumulate in the thoracic, abdominal and pericardial cavities due to the significant increase in the permeability of the blood vessels after the injection, which can lead to a decrease in blood volume, electrolyte disorders, blood concentration, abdominal hemorrhage, thrombosis and other adverse reactions, at this time, it is necessary to consult a doctor for timely examination and removal of excessive body fluids, so as not to affect the patient’s health.