Abstract:[Objective] To evaluate the diagnostic value of iliac-lower extremity line in hip ultrasound for developmental dysplasia of the hip (DDH) in infants. [Methods] The hip ultrasound examination was conducted in 863 infants by Graf method, and the relationships be- tween iliac-lower extremity line and femoral head in different Graf types of the hip were determined. The age, sex, α angle, β angle and Graf types of the hip were compared between the positive and negative groups of the iliac-lower extremity line. [Results] At the primary ultra- sound examination of the 863 infants, the iliac-lower extremity line positive group was significantly younger than the negative group in age [(53.2±25.3) days vs (67.7±34.0) days, P＜0.001], and the positive groups had significantly higher ratio of female than the negative group [male/female, (69/108) vs (340/346), P＜0.001]. In addition, the positive group got significantly less alpha angle [(53.7±4.6)° vs (60.1±4.5)°, P＜0.001], while significantly greater β angle [(77.5±6.0)° vs (71.9±6.0)°, P＜0.001] than the negative group, despite of no statistically signifi- cant difference in Graf type of the hips between the two groups (P＞0.05). [Conclusion] As Graf method is used to detect the hip in infants, the iliac-lower extremity line might be helpful for judging whether the femoral head is displaced related to the acetabulum.