Thirty newborn pigs within 3 days of life were randomly divided into different groups according to the time of hypoxic-ischemic encephalopathy. The results showed that the brain damage and pathologic changes were most obvious in the 60 min hypoxia-ischemic group. Brain edema was observed in every group, especially in the group where hypoxia-ischemic lasted for more than 30 min. Cerebromalacia and hemorrhage in ventricles of brain and in arachnoid were observed, and these were particularly noticed in the group where hypoxia-ischemia lasted for 60 min.