[ ] Objective To explore the diagnostic value of prenatal ultrasound in diagnosis of fetal external ear。Methods Totally 20 fetus with external ear were screen out in our hospital during system screening ultrasound examination , and the images were stored . Results 20 cases with abnormal external ear in pregnant women were totally confirmed by postpartum ,11 cases were bilateral low set ears , 2 cases were bilateral microtia , 3 cases were on the right side of the small ears , 1 case was bilateral microtia with low set ears, 3 cases were right accessory ear , and 1 case of anotia was missed diagnosis . Conclusion Three-dimensional ultrasound can be used to improve the diagnostic rate of fetal external ear deformities .