Purpose To assess the clinical efficacy of ultrasonography in developmental dysplasia of the hip in infants. Methods 32 positive infants were treated,all were examined with the Grafe and Morin technique of hip sonography during the treatment,to assess the clinical efficacy and guide the clinical treatment. Results All of the 32 infants turned into normal types,there was statistical significance in the different αangle after the treatment. there was also statistical significance in the measurement of femoral head coverage. One type Ⅳ hip failed reduction after Pavlik harness treatment,but it turned into normal types after changing to spica casting in time. Conclusion The Grafe and Morin technique of hip sonography during the treatment of DDH is effective,it plays an important role in supervision and guidance during the treatment.