Embryo transfer is one of the important parts in the IVF treatment process. Currently, embryo transfer is performed under the guidance of abdominal ultrasound in many reproductive medicine centers in China and abroad. The advantages of abdominal ultrasound-guided embryo transfer are: the outer tube of the embryo transfer tube enters the inner uterine opening visually, clearly and easily; then, the inner tube enters the uterine cavity in a clear and accurate position. Especially, it is more advantageous for those difficult transfers where the cervical canal – endocervix has been damaged or the tube is deformed. Only with proper urine volume, the abdominal ultrasound can visualize the condition of the cervical canal and uterine cavity of the uterus, which facilitates the embryo transferee to enter the uterine cavity smoothly. Therefore, it is important for the patient to have the proper amount of urine before embryo transfer, and not to think that more is better, nor less is better.