Abstract: Objective To investigate the correlations between neonatal hypoxic ischemic encephalopathy(HIE)and levels of arterial blood lactic acid as well as cerebrospinal fluid lactic acid. Methods Twenty-eight children with HIE(including 6 mild cases, 11 moderate cases and 11 severe cases)and 28 controls were selected, and levels of arterial blood lactic acid and cerebrospinal fluid lactic acid were compared between the two groups. Results The levels of arterial blood lactic acid and cerebrospinal fluid lactic acid in the HIE group were significantly higher than those in control group, and the levels of arterial blood lactic acid and cerebrospinal fluid lactic acid increased significantly with the aggravation of the disease(P<0.05). There were no significant differences in the levels of cerebrospinal fluid lactic acid and arterial blood lactic acid between the group with 1 min Apgar score ≤ 3 points and group with Apgar score of 4 to 7 points(P>0.05), but the levels of cerebrospinal fluid lactic acid and arterial blood lactic acid in group with 5 min Apgar score ≤ 5 points were signifiantly higher than those in group with 5 min Apgar score >5 points(P<0.05). Conclusion The levels of arterial blood lactate acid and cerebrospinal fluid lactate acid can reflect the severity of HIE, and have important value for early diagnosis, treatment and prognosis of children with HIE.