Abstract: The three-dimensional ray model BELLHOP3D can be used to calculate the three-dimensional sound field in the ocean, which is of great significance in practical applications such as sonar performance prediction and marine environmental parameter inversion. However, with the increases of the calculated sea area and the resolution improvement of the calculated grid points, the computational demand of underwater acoustic propagation is also gradually increased. In this paper, the parallelization in the computing process of BELLHOP3D is studied, and the OpenMP multi-core parallel technique is used to realize the multi-core parallilzation of BELLHOP3D on Tianhe Ⅱ platform. Finally, the parallel computational efficiency of the ray model is tested in the 2D Munk waveguide case and the 3D wedge-shaped seabed case. When all the 24 computing cores in the computing node of Tianhe Ⅱ are used for calculation, the parallel computational efficiencies for the two examples reach 83.3 % and 87.5%, respectively.