Objective To determine the diagnosis and clinical classification of transcranial doppler sonography(TCD) and CT plain scan for neonatal hypoxic ischemic encephalopathy (HIE). Methods The clinical cases and follow-up data of 68 asphyxia neonates with HIE in the neonatal ward of our hospital from May 2016 to May 2018 were retrospectively analyzed. According to the data, all neonates underwent TCD and CT scans, and the diagnostic coincidence rate of TCD and CT plain scan for HIE was summed. The ultrasound blood flow of different levels of HIE patients and the characteristics of related images in ultrasound and CT plain scan were analyzed. Results Compared with those in children with mild HIE, Vd, Vs, and Vm of the middle cerebral artery were significantly lower in the moderate and severe HIE group, while PI and RI were significantly higher. In the anterior cerebral artery, Vs increased slightly, while Vd, Vm, PI and RI were significantly higher than those in neonates with mild HIE (P＜0.05). The diagnostic coincidence rate of TCD for HIE was significantly higher than that of CT plain scan (χ2=5.423, P=0.020). Mild HIE in the TCD examination showed diffusely enhanced hyperechoic region beyond the triangle of lateral ventricle, and the echo was lower than the choroid plexus. Moderate HIE showed an uneven echo around the lateral ventricle, and the echo intensity is similar to that of the choroid plexus. In severe HIE, the diffuse echo of the brain parenchyma is enhanced, which is higher than that of choroid plexus. CT plain scan showed mild HIE can be seen with patchy and low density lesions in the brain lobe. Moderate HIE can present petal-like and patchy lesions in the brain lobe. The boundary between gray matter and white matter of the brain was not clear, and the signs of intracranial hemorrhage can be combined. In CT plain scan, severe HIE mainly presents diffuse low-density lesions in the brain parenchyma, the boundary between gray matter and white matter of the brain disappeared, the reversal sign and/or intracranial hemorrhage were observed, and multiple density points appear in the white matter of the brain. Conclusion Compared with CT plain scan, the diagnostic coincidence rate of TCD for HIE is significantly higher, and the dynamic observation for neonatal cerebral blood flow is more clear, which is more favorable to assess the HIE classification and severity of the disease, and further guide clinical treatment to improve the prognosis of the child.