Endometrial thickness of 16mm may be a normal physiological change and generally not harmful, or it may be a manifestation of endometrial hyperplasia, endometrial polyps, endometrial cancer and other diseases, which may cause menstrual disorders, affect the patient’s reproductive function, threaten life and other hazards. The endometrium is regulated by ovarian hormone levels and has a cyclical process of proliferation and shedding, generally 8~10mm in thickness during the proliferative phase, followed by continued thickening during the secretory phase, with a thickness of 10~15mm, and a few patients may also reach 17mm, therefore, endometrial thickness of 16mm may be a normal physiological change, and will not have any special harm. However, endometrial thickness of 16mm may also be a pathological thickening caused by endometrial hyperplasia, endometrial polyp, endometrial cancer and other diseases, which may cause symptoms such as menstrual disorders or vaginal bleeding, and may also affect the fertility of the patient. In case of endometrial cancer, it may be life-threatening in serious cases. It is recommended to go to the hospital in time for relevant examination to clarify the cause and then carry out active treatment.