Abstract: In 3D finite element analysis, hexahedral meshes are considered ideal volumetric meshes due to their advantages in terms of analysis accuracy and convergence efficiency. However, the automatic generation of hexahedral meshes for complex models remains a challenging task. To address this issue, a hex-dominant mesh generation method based on swept volume decomposition is proposed. First, a high-quality frame field is generated to guide the identification of swept volumes and the generation of swept meshes. Then, potential swept sub-volumes are iteratively identified based on the singular lines and streamlines of the frame field, followed by the construction of cutting surfaces aligned with the sweeping directions. Finally, high-quality swept meshes for the swept sub-volumes are generated based on the frame field, and a topologically compatible hex-dominant mesh is generated for the remaining non-swept sub-volumes using the merging method. The experimental results of six geometric models demonstrate that the proposed method can efficiently identify swept volumes with significant directional variations or severe intersections within the model, and the generated hex-dominant meshes exhibit superior performance in terms of scaled Jacobian values and generation efficiency.