Abstract: Global acoustic simulations are significant in revealing the internal and physical structure of the Earth. However, due to the limited flexibility of grids and the difficulties in handling boundaries, the traditional finite-difference method (FDM) is usually less used in global simulations. Nevertheless, these issues can be well resolved by employing a multi-block structured grid to discretize circular regions. In this paper, we propose an O-H grid approach to partition the circular region and utilize the curvilinear grid finite-difference method (CGFDM) to solve the acoustic wave equation within this circular domain. By appropriately stretching the grid, the interconnections between each grid block are sufficiently smooth for stable information exchange. To verify the efficacy of this method, we conducted three numerical experiments, by comparing results with alternative approaches. Our test results demonstrate good agreement between our findings and the reference solutions. Since the proposed algorithm can effectively solve wave propagation problems in circular regions, it can contribute to 2D global simulation, particularly in interpreting the Earth’s interior.