Letrozole does not promote endometrial growth. Letrozole can promote ovulation treatment, mainly by lowering the level of estrogen in the body, and after the estrogen drops, it will feed back to the central mechanism to produce more folliculopoietin, so it will have the function of promoting ovulation, in order to make the follicles grow and develop, and achieve the purpose of promoting successful ovulation. Since it reduces estrogen in the body, it does not cause the endometrium to grow and does not have this function. The application of letrozole to promote ovulation must be under the guidance of a doctor. If the endometrium is relatively thin, it is recommended to find out the cause and then give the appropriate treatment according to the cause.