Abstract: Overlapping grid techniques, from two major aspects, the grids assembly process and the interpo-lating computations in the numerical iterations, are reviewed in this paper. First, the grid assembly algorithms in the preconditioning step are discussed from two aspects, including the hole-cutting algorithms and the node-searching algorithms for building inter-grid links. Secondly, the interpolation methods for communication among overset grids in the numerical computations are illustrated. Meantime, the issues of conservative laws for in-compressible and compressible flows are discussed and the accuracy of interpolation is analyzed. The parallel implementations of overset grids and achievements in engineering applications are also reviewed. Finally, some conclutions are reached. There are wide spaces for further studies of overlapping grid techniques, such as the improvements of grid assembly,the interpolation and the parallel computations.