Objective：To analyze the dynamic changes of cerebrospinal fluid test results in early course in the neonatal purulent meningitis. Methods：In four hundreds and seven neonates who were admitted to five hospitals including the Children’s Hospital of Chongqing Medical University and Shanxi Provincial People’s Hospital during 2010 to 2014，thirty-eight full-term infants without any antibiotics before the lumbar puncture were enrolled in this study. The data were collected retrospectively. Children’s clinical manifestations and cerebrospinal fluid test results were collected to calculate their median for each parameter in different time peri－ods. The natural dynamic changes of cerebrospinal fluid test results without the antibiotic interference were analyｚed. Results：①Neonatal purulent meningitis often lacks the typical clinical manifestations. The main manifestations were fever（30/38，78.95%），and only about 1/3 of the cases have central nervous system involvement manifestations，like apathy or lethargy（14/38，36.84%） and/or convulsions（12/38，31.58%）. ②Most of the main indicators of cerebrospinal fluid within 24 hours were in the normal range. Within the passage of course of disease，there was a dynamic process in cerebrospinal fluid results. The results of cerebrospinal fluid exami－nation showed that，within the first week of the course，the cell number and protein of cerebrospinal fluid reached their peak on the third day and then began to decline. However，the concen－tration of sugar in cerebrospinal fluid was the lowest on the third day after the beginning of disease，and then increased. The chloride levels in cerebrospinal fluid increased only slightly on day 3. Conclusion：Lumbar puncture is the key experimental evi－dence of neonatal purulent meningitis，but we should be alert the false negative cerebrospinal fluid for the infants in early course. Re－peating the lumbar puncture in 2-3 days after the disease can often get more obvious abnormalities.