Objective To assess the role of hip ultrasonography in the early screening and following up of developmental dysplasia of the hip (DDH). Methods A total of 1324 hips of 662 infants younger than 6 months underwent ultrasonography with Graf method. The sonographic appearances of bony roof, superior bony rim, cartilaginous roof, as well as α and β angle measurements were classified according to the Graf method. Risk factors such as gender, sides, fetal position, and swaddling used were assessed. Following up were performed with ultrasonography in the cases of immaturity, dysplasia and dislocation that needed to be monitored or treated. Results Detection rate of selective ultrasound in screening of DDH of the hip was 7.42%. Both gender and fetal position was the risk factor of DDH. Twenty-seven infants with dysplasia hip and five with dislocation hip were followed-up with ultrasonography during treatment process. Thirteen infants with dysplasia turned to normal after abduction exercises, while other fourteen received treatment in Pavlik harness for no improvement in ultrasonography. All infants of dislocation received operation eventually because of failing to Pavlik harness. Conclusion Ultrasonography can objectively assess the development of DDH, monitor the course of following-up and treatment of DDH, and serve as a main tool in the early screening and following up of DDH in infants.