To explore the synergistic mechanism of Rhizoma Atractylodis Macrocephalae (RAM) combined with Ginseng Radix et Rhizoma(GRR) in the treatment of chronic atrophic gastritis(CAG),this article comparatively studied the composition of volatile oil RAM and volatile oil after RAM combined with GRR and their effects on expressions of aquaporin(AQP) 3 and AQP 4 in gastric tissue of rats with CAG.The volatile oil of RAM and the volatile oil after RAM combined with GRR were extracted by steam distillation,and characterized by gas chromatography and mass spectrometry(GC-MS) technology.Rats were randomly divided into blank group,model group,RAM volatile oil group and compatible volatile oil group.MNNG was used to establish the CAG model.The microscopic and ultrastructural changes of the gastric mucosa and the expression of AQP 3 and AQP 4 in each group were observed after administration.The results showed that the amount of volatile oil extracted from RAM was increased when combined with GRR.According to the records of GC-MS,the relative contents of atractylone was decreased after combination,and a small amount of GRR volatile oil was added.Microscopic and ultramicroscopic observations showed that gastric mucosa of rats in the model group were folded and wrinkled,and the glands in the mucosal surface and lamina propria were atrophied seriously,resulting in the morphological changes of gastric pits and damage of epithelial cells.In addition,gastric mucosa was accompanied by extensive infiltration of inflammatory cells,so the pathological score was significantly higher than that of the normal group (P<0.05).Compared with the model group,the two administration groups improved the above pathological results,and the compatible volatile oil group performed better.The immunohistochemistry results showed that expression of AQP 3 and AQP 4 in the gastric mucosa of the model group was significantly lower than that of the blank group (P<0.05).Compared with the model group,expressions of AQP 3 and AQP 4 protein in the gastric mucosa of each drug group tended to increase or significantly increase,and the compatible volatile oil group is better than the RAM volatile oil group.The above results indicated that the volatile oil of RAM before and after combined with GRR had therapeutic effects on CAG,and the oil after combination possessed better effects.The increasing efficiency might be due to the decrease of the ratio of atractylone the addition of a small amount of GRR volatile oil and the up-regulation of AQP 3 and AQP 4 expression.