[Objective] To investigate the early evolution process of hip development in premature newborn and infants. [Methods] A prospective study was conducted on 4102 neonates who were born in Yangzhou Maternal and Child Health Hospital from January 2019 to June 2021. Graf hip ultrasound was conducted at 1, 7, 42 and 90 days after birth to observe the early development and conversion of the hip. [Results] According to the diagnostic criteria of premature neonate, 393 cases were of the premature, accounting for 9.58%, whereas 3709 cases were of the normal term neonates, accounting for 90.42%. The premature had significantly lower body weight (P<0.05) , and sig- nificantly higher ratios of multiple births, maternal hypertension and placenta previa than the mature (P<0.05) . At the 1 and 7 days after birth, the premature group had significantly higher proportion of Graf type I hip than the mature group (P<0.05), whereas which became not statistically significant between the two groups at 42 and 90 days after birth (P>0.05) . With the increase of postnatal age, the α angle signif- icantly increased (P<0.05) , while the β angle significantly decreased in both groups (P<0.05) . At all matching time point after birth, the premature group had significantly greater α angle, while significantly less β angle than mature group (P<0.05) . Among the 393 preterm in- fants, 32 were of early preterm (28~31 w) , 64 were intermediate preterm (32~33 w) , and 297 were late preterm (34~36 w) . At 1 and 7 days after birth, late preterm group had significantly lower proportion of Graf type I hip than the early preterm group and the intermediate pre- term group (P<0.05) , whereas which turned to be not statistically significant at 42 days after birth in Graf grades of the hip among the three groups (P>0.05) . [Conclusion] The preterm neonates have higher proportion of Graf type I hip than the matures, additionally, 42 days after birth is a reasonable time for the first screening of preterm neonates.