The fluctuation curve of basal body temperature allows a professional gynecologic endocrinologist to see whether the measured menstrual cycle is ovulating, whether sex is effective, whether pregnancy is present, whether luteal function is good, etc. Therefore, basal body temperature measurement is the most cost effective and accurate tool for patients with menstrual irregularities and infertility. An experienced gynecologic endocrinologist can also analyze the effectiveness of medications and guide the decision on the follow-up treatment plan by using the patient’s basal temperature chart. The basal body temperature can indirectly reflect the ovarian function of a woman. The basal body temperature of normal reproductive women is slightly lower after menstruation and may or may not be lower on the day of ovulation, but it rises after ovulation due to the production of the corpus luteum by the incubating follicles and then falls again until the next menstruation. Basal body temperature can be measured to know the presence or absence of corpus luteum and the function of corpus luteum, so as to know the presence or absence of ovulation and to estimate the date of ovulation, which is very important for the diagnosis and treatment of patients with ovarian dysfunction and infertility and for the observation of the efficacy. Please follow the instructions and doctor’s orders to perform the following items correctly: 1. Prepare a Celsius thermometer, master the reading method and make sure it is accurate. 2.Place the thermometer next to the bed and swing down the mercury column every night before going to bed. 3, every morning after waking up, immediately measure the sublingual body temperature for 5 minutes. If you can take the temperature at a fixed time (5:00 a.m. to 7:00 a.m.) every morning, it is better. Before taking the temperature, it is strictly forbidden to get up, urinate and defecate, smoke, eat, talk, etc. After measurement, record the temperature into the table. 4, such as sexual life, should be indicated in the table. 5.Cases such as cold, drinking, late sleeping, insomnia, etc., often affect the temperature, should be written in the notes for reference. 6.If there is any transient lower abdominal pain, vaginal bleeding, leucorrhoea, increased sensuality or other abnormalities during the cycle. These should be noted in the comments. 7.The start and stop dates of examination, treatment and medication should be indicated in the remarks. 8.A table should be used for each menstrual cycle, starting from the left side of the table, with x indicating the beginning of the menstrual period.