At present, the piecewise rigidization method in mechanics of materials is not explained in detail, which is only applies to solve the deformation of beam. In fact, it is a kind of superposition method. As a basic method in mechanics of materials, it can be applied to solve a variety of problems, especially complex mechanics problems. Based on the analysis of principle of the piecewise rigidization method, combining with my own teaching experience, the application is discussed in depth on the statically indeterminate tension and compression bar, stepped shaft, non-uniform beam and plane rigid frame.