Objective To study the pathological changes in some important brain areas of rats with post-traumatic stress disorder (PTSD) induced by combined stress.Methods Twenty healthy adult female SD rats were randomly divided into normal group and model group, with 10 rats in each group. The PTSD model was established by combined stress. After 4 weeks, the rat behaviors of the two groups were tested by elevated plus maze and Morris water maze. After the test, samples of the cerebral cortex, areas of CA1, CA2, CA3 and hippocampal dentate gyrus were taken for pathological examination using HE and Nissl staining. Results In the normal group, the cell morphology and distribution were regular and the cell nucleoli were clear in the cerebral cortex and hippocampus, cytoplasmic Nissl bodies were abundant, and there were no obvious neuronal degeneration and necrosis. In the model group, the cell morphology and distribution in the CA1 and CA3 areas were irregular, with increased cell gaps, and in addition, there were some pathological changes of physaliferous cells, especially in the CA3 area. The cell morphology and distribution in the CA2 area were regular. In the dentate gyrus, some cells arranged loosely, the cell gap was widened, and the amount of Nissl bodies was decreased. Conclusions There are some pathological changes in the hypocampal CA1, CA3 and dentate gyrus in rat models of post-traumatic stress disorder, and they will provide an experimental basis for studying the pathological mechanism of PTSD patients.