Objective To study the effects of malondialdehyde (MDA), superoxide dismutase (SOD) and tumor necrosis factor-α (TNF-α) on brain tissue in rats with pancreatic encephalopathy (PE). Methods Thirty-six Wistar rats were randomly divided into control group (n=6) and PE model group (n=30). In control group, rats were injected with normal saline by internal carotid artery (0.1 ml/100 g) and were killed on the first day after the injection. In PE model group, rats were injected with phospholipases A2 (0.1 ml/100 g, 1 000 U/0.1 ml) by internal carotid artery, to establish animal model of PE in rat and 10 rats were killed on day 1, 3, 7 respectively after the injection. The changes of water content in the brain were measured. Leucocytes aggregation and margination in the microvessels, and the changes of cerebral cells and nerve fibers were observed. The levels of MDA, TNF-α and the activity of SOD were tested in the brain homogenate in rats. Results In PE model group, water contents of brain increased; The phenomena of leucocytes accumulation and margination, cellular edema of neurons and demyelination of nerve fibers became more obvious; The levels of MDA and TNF-α increased significantly than those in the control group, while the activity of SOD reduced (P＜0．05， P＜0.01)． Conclusion Inthe rat model of PE, MDA, SOD, and TNF-α play important roles on the occurrence and development of brain injury.