The Chimera grid methods have been widely used in the computation of flow over complex configurations or unsteady moving boundary process. In this study, the Cartesian auxiliary grid is introduced into the multi-block structured grid system. The background mesh is used to replace the spatial structural grid, and the mixed mesh system of the Cartesian auxiliary mesh and the multi-block structured mesh is established. By means of background grid, the occupation of computing resources is reduced, and the fast establishment of the boundary and interpolation relationship between meshes are realized. On this basis, the parallel overlapping process of hybrid mesh is realized. Through the definition and application of overlapping weights of overlapping grids, the parallel distribution pattern and load balancing model of hybrid grids are established, which can effectively reduce the communication of overlapping interpolation information among different processes, and realize the uniform distribution of computing and communication load among processors.