【Abstract】Objective To analyze the clinical value of ultrasound in diagnosing thanatophoric dysplasia (TD) in early prenatal.Methods The ultrasonographic features of 5 fetus with TD were analyzed. The nuchal translucecy, crown-rump length, biparietal diameter and femur length of 5 fetal with TD and 563 normal fetal were compared. Results The nuchal translucecy of TD fetal were significantly thicker than that of the normal fetal. The ratio of femur length/crownlimp length and femur length/biparietal diameter of TD fetal were different from that of normal fetal (P ＜0.05).Conclusion Early prenatal ultrasound can make accurate diagnosis for TD，FL/CRL and FL/BPD ratio is expected as abnormal value standard of long bone.