Impeller,a core component of pump equipment, is related to the stability and safety. In order to improve the accuracy and efficiency of numerical simulation, a new method of hexahedron mesh for impeller of pump based on topological segmentation is proposed. Firstly, the topological structure theory of threedimensional model is analyzed; Secondly, the hexahedral mesh generation method based on mapping theory is studied to obtain the virtual computing domain model;Thirdly, the mesh quality is optimized and the mesh size is controlled; Finally, the full hexahedral finite element method is developed with the pump impeller as an example. The finite element meshing method is verified by using ANSYS software. The results show that the allhexahedral meshes model has the characteristics of high mesh quality, strong antidistortion ability, small scale and efficiency.