Objective The aim of this work was to investigate the protective effects of 13?methyltetradecanoic acid (13?MTD) on focal cerebral ischemia in rats and oxygen paradox in cultured astrocytes in vitro. Methods Almost pure astrocytes were obtained after primary culture and subculture from cerebral cortex of neonatal rats, and then the OGD 10 h/R 24 h cell model was generated by treatment with oxygen?glucose deprivation for 10 h/ reperfusion for 24 h. 13?MTD 20, 40, 80 μg/ mL was administered immediately after reperfusion. Microscopy was used to observe the changes of cell morphology dynamically. MTT assay was employed to detect mitochondrial activity, and immunohistochemistry was done to determine the expressions of GFAP and AQP4. Results After oxygen paradox, damages of the cerebral cortical astrocytes of neonatal rats were observed, the mitochondrial activity was decreased significantly ( P < 0. 01), and AQP4 protein expression was increased significantly ( P < 0. 01). Compared with the vehicle control, 13?MTD 20, 40, 80 μg/ mLimproved the above parameters ( P < 0. 01), with optimal effect being obtained at 80 μg/ mL. Conclusions 13?MTD can down?regulated AQP4 protein expression, improve the mitochondrial activity, decrease cell edema, and protected the astrocytes damage from oxygen paradox.