Endometrial tolerance refers to the ability of the endometrium to allow blastocyst positioning, adhesion, penetration, implantation, and embryo implantation and development. Endometrial tolerance is closely related to embryo implantation and is one of the key factors in determining the success of assisted reproductive technologies. Ultrasonographic assessment of endometrial tolerance includes endometrial thickness, endometrial type, hemodynamic parameters of the endometrium, such as resistance index, pulsatility index, and endometrial vascular index, and blood flow index. Most current studies have shown that the clinical pregnancy rate is significantly higher in type A endometrium than in type B and C endometrium. Endometritis, uterine adhesions, and endometrial hyperplasia may affect endometrial tolerance, and tubal effusion also affects endometrial tolerance, thus affecting pregnancy. Further treatment is needed to improve the endometrial tolerance according to the test results.