Objective: To explore the value of high and low frequency ultrasound in the evaluation of neonatal brain development, gestational age and birth weight.Methods: A total of 100 children hospitalized in the neonatal intensive care unit of our hospital from June 2016 to June 2018 were enrolled.According to the gestational age at birth, the children were divided into 4 groups: group A: 29~32 weeks (4 cases), group B 32~34 weeks (18 cases), group C 34~36 weeks (20 cases), group D 36 More than week (58 cases).High and low frequency ultrasound combined with brain detection were performed in all newborns.Compare the birth weight of newborns in different gestational weeks, the average gray value of different brain tissue, the length of the corpus callosum and cerebellum.Correlation analysis was performed on the gestational age, the birth weight, the length of the corpus callosum and cerebellum, and the average gray value of different brain tissues.Results: There was no significant difference in gender contrast between the different gestational weeks (P>0.05). There was a significant difference in the birth weight of newborns in different gestational weeks. The newborns in group A had the lowest body weight, followed by group B and group C. The body mass of group D was the largest (P<0.05). There was no significant difference in the birth weight between group B and group C (P>0.05). The differences of neonatal thalamic basal ganglia, frontal white matter, occipital white matter, corpus callosum length and cerebellar vermis length were statistically significant (P<0.05). The lengths of corpus callosum and cerebellar vermis were from group A to group A. In group B, group C and group D, the mean gray value of the same brain tissue from small to large was in group D, group C, group B and group A, and the difference was statistically significant (P<0.05).Correlation analysis showed that the gestational age and birth weight were significantly negatively correlated with the average gray value of the basal ganglia, frontal white matter and occipital white matter (r<0, P<0.05), and the length of the corpus callosum and the length of the cerebellum. There was a significant positive correlation (r>0, P<0.05).Conclusion: High and low frequency brain ultrasound can detect the average gray value, carcass length and cerebellar crest length of different brain tissues of newborns, which can provide a reliable evaluation basis for clinical brain development and reduce the subjectivity of analysis.