Abstract: Objective To explore the diagnostic value of pubo-femoral distance(PFD) measured by different body positions ultrasound in the screening of developmental dysplasia of the Hip(DDH). Methods A total of 65 children with suspected DDH diagnosed by ultrasound combine with clinical feature from March 2017 to March 2019 in our hospital and the first people's hospital of Xiaoshan district of Hangzhou were enrolled as DDH group, while 69 healthy children were enrolled as control group. All children were examined by ultrasonography. PFD, α angle and bone rim percentage(BRP) were compared. ROC curve was used to evaluate the diagnostic efficacy of different indexes in DDH screening. Results The α angle, BRP in the DDH group were lower than those in the control group(all P<0.05). The PFD in the DDH group was higher than that in the control group(P<0.05). The ΔPFD in the male and female children with DDH were higher than those in the control group(all P<0.017). The ΔPFD in the unilateral and bilateral DDH patients were higher than those in the control group(all P<0.017). The best cut-off point of PFD screening DDH was 5.03, AUC was 0.988, which was significantly better than α angle and BRP(Z=3.747, 4.966; all P<0.001). The diagnostic sensitivity of PFD was 90.14%, which was significantly better than other indexes(P<0.05). Conclusion The diagnostic efficacy of PFD for screening DDH is prominent and better than α angle and BRP, and the difference of PFDs between the two hips is independent of the sex of the child. PFD may become one of the observation indexes of ultrasonic diagnosis of DDH.