Abstract: 　Objective　To explore the effect of progesterone on the expression of O4 and O1 in the white matter of neonatal rat model with periventricular leukomalacia (PVL). Methods　2-day-old neonatal SD rats were randomly divided into model group, experimental group, and sham operation group. Rats' left common carotid artery was ligated and exposed to hypoxia (8%O2+92%N2) for 0.5 h in both the model group and experimental group to build the PVL animal model. The rats in experimental group was injected intraperitoneally with progesterone 10 mg/(kg·d) immediately after cerebral hypoxia ischemia. In sham operation group, rats' left common carotid artery was only isolated without ligation and hypoxia. 1, 4, 7, and 14 days after operation, the pathological changes of brain tissue were compared among three groups. Immunohistochemical staining was used to detect the expression of O1 and O4 in the cerebral cortex of rats in three groups at different time points. Results　There were no abnormal pathological changes in the white matter in the sham operation group at each time point. The left ventricular enlargement and periventricular leukomalacia were found in both model and experimental groups, while the pathological damages of white matter in experimental group were significantly lighter than those in model group at each time point. The integral optical density (IOD) of O1 and O4 positive cells in the cerebral cortex of the three groups was gradually increased at day 1, day 4, and day 7 after operation and reached the peak level at day 7 , then was decreased at day 14 after operation. There was statistically significant difference (P<0.01). At day 1, day 4, day 7, and day 14, the integral optical density (IOD) of O1 and O4 positive cells in the cerebral cortex of sham operation group was highest, followed by experimental group and model group, and there was significant difference (P<0.01). Conclusion　Progesterone can reduce the pathological damage in the cerebral cortex in neonatal rats with PVL, and promote the expression of O1 and O4 in the periventricular white matter, which can promote the differentiation and maturation of oligodendrocytes.