The overset grid is widely used for numerical simulation of the complex configuration and multi-bodies separation problems. However, the practicability and robustness of hole-cutting for the large scale grid is still a bottleneck problem. In this paper, a parallel implicit hole-cutting method for the unstructured overset grid is developed. The boundary between the active and the negative regions is determined by wall distance and donor cell searching. The front advancing method is adopted to identify the active region. The parallel strategy is implemented based on the partitioned grids. To reduce the memory consumption of the large scale grid, Alternating Digital Tree (ADT) is built merely on each sub-zone. Global nodes are searched in the sub-zones of the present processor, and their status is finally determined through Message Passing Interface (MPI) communication. This parallel method is highly automatic and can be used for the large scale grid. The practicability and robustness of the method proposed is verified by several hole-cutting and the wing/store configuration separation test cases.
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