Three-dimensional finite element method (FEM) is widely used as an effective numerical simulation technique to solve the complex engineering problem. Usually, the more complex engineering problem has more complex structure and shape; the FEM simulation technique is that needs to discrete the structure and shape of the problem by mesh. In addition, the correct generation of mesh is one of the most significant issues that directly affect to the accuracy of the FEM simulation. The hexahedral mesh is better than tetrahedral mesh in solving the complex engineering problem. The common methods of hexahedral automatic mesh generation have been used in some commercial soft already, but its adaptation is not enough to solve for practical applications of the complex engineering problems. A new method of mesh generation technique was proposed by improved waveform mesh generating method, and realized by C++ developing program in Linux OS. The method could generate some effective and smoothly mesh models by quadrilateral element or hexahedron element, and not only generated revolution curve surface meshes, but also generated random meshes according to free functions too. The results shown that the hexahedral mesh models of the complex shapes were generated as the shape function apply to regular mesh side as a waveform constraint.