Background and Aims Esophageal hiatal hernia is a common surgical condition, which is usually treated by tension-free mesh repair in clinical practice. However, there is still a relative lack of experimental data on the selection and application effectiveness of different types of meshes in esophageal hiatal hernia repair. Therefore, this study was conducted to compare the effects of fixing polypropylene mesh and composite mesh on the surrounding tissues and their own shrinkage at the diaphragmatic defect in rats, in order to provide reference for the selection of esophageal hiatal hernia meshes in clinical practice.Methods Male Sprague-Dawley rats underwent exposure of the gastroesophageal hiatus by separating the gastroesophageal junction from the liver. A lightweight polypropylene mesh (polypropylene mesh group) or a composite mesh (composite mesh group) was respectively fixed to the diaphragmatic tissue at the hiatal hernia site using monofilament sutures, or no mesh fixation was performed (sham surgery group). Body weight and food intake of each rat in each group were recorded at postoperative day 7, 15, and 30. Rats were sacrificed after 30 d, and the degree of mesh shrinkage, adhesion strength, and histopathological changes in the diaphragmatic tissue were analyzed.Results There were no significant changes in body weight and daily food intake before and after surgery in all groups (all P>0.05). The extent and severity of adhesion between the diaphragmatic tissue and the mesh were significantly lower in the composite mesh group than those in the polypropylene mesh group (both P<0.05). Both mesh types showed mesh shrinkage, but the postoperative mesh area was significantly larger and the shrinkage rate was significantly lower in the composite mesh group than those in the polypropylene mesh group (both P<0.05). Compared to the sham surgery group, local muscle fiber atrophy, as well as infiltration of inflammatory cells such as lymphocytes and macrophages, were observed in the diaphragmatic tissue of both the polypropylene mesh group and the composite mesh group. The fibrous encapsulation layer of the diaphragmatic tissue in the composite mesh group appeared thicker, but the adhesion was thinner, easily separated from the intra-abdominal organs. Compared to the sham surgery group, the expression of surface markers for macrophages (CD68) and T lymphocytes (CD3) in the diaphragmatic tissue was significantly increased in both the polypropylene mesh group and the composite mesh group, but the proportion of positive cells expressing CD68 and CD3 was significantly lower in the composite mesh group compared to the polypropylene mesh group (both P<0.05).Conclusion The composite mesh is superior to polypropylene mesh in terms of adhesion, inflammatory response, and mesh shrinkage, and it has good biocompatibility and stability, therefore, it is recommended for clinical use.