对49例并低渗性脑病的病例进行分析，显示严重低血钠是发生该病的主要原因。原发病以颅脑疾患和肺部感染为多见；缺氧、感染、利尿剂应用不当可促使低渗性脑病的发生。对危重新生儿及时进行血生化和血渗透压检查，是该病早期诊断的关键。 49 cases and hypotonic encephalopathy cases were analyzed, showing that severe hyponatremia is the main reason for the disease. Primary disease with craniocerebral disease and pulmonary infection is more common; hypoxia, infection, inappropriate use of diuretics can promote the occurrence of hypotonic encephalopathy. Timely diagnosis of critically ill newborns blood biochemical and blood pressure, is the key to early diagnosis of the disease.