Abstract: Torsion is one of the four basic deformation modes involved in material mechanics. Through many years of teaching, the authors found that it is difficult for teachers to teach knowledges of torsion analysis, and it is also challenging for students to understand. In order to tackle this problem, this article tries to change the instruction order. The special circumstance of thin-walled circular tube is first introduced. Then the general hollow and solid circular shaft situations are focused. This reflects the common shallow-to-deep gradual understanding way. Furthermore, the application scope of plan hypothesis is qualitatively discussed based on torsional stress and deformation characteristics of non-circular closed thin-walled shaft.