Three-dimensional finite element analysis of the consolidation of composite ground was carried out in detail within the influence scope of a single granular column. Due to the different mesh sizes of granular column and soil set, several calculation conditions were gained first. Then, the numerical solutions for consolidation degree and excess pore pressure of different conditions were compared with analytical solution. Subsequently, the significant level of errors caused by different meshing schemes was obtained. It was found that deviations caused by different meshings decreased with the development of consolidation. The gridding of the soil around the granular column was the main source of error within three mesh schemes. The ground mesh in the direction of depth has no obvious effect on the overall consolidation degree, but it had a greater impact on the result of excess pore pressure in the shallow. The gridding of the granular column had little effect on the calculation result of consolidation, so it can be described by one unit in FEM. The above findings can be used to guide the finite element analysis of a reasonable mesh.