Abstract: In the teaching system of Mechanics of Materials, the torsion problem of single-cell thin-walled bars is a conventional teaching content, and its research method can be extended to multi-cell thin-walled members. The torsion problem of multi-cell members belongs to a statically indeterminate problem, which requires establishing the deformation compatibility condition that the torsion angle per unit length of each cell is equal. This paper adopts the unit load method to simplify the derivation of the torsion angle, and solves the shear flow of each cell by combining equilibrium equations with deformation compatibility conditions. Meanwhile, different equivalent systems are adopted at different solving stages to reduce computational complexity. The proposed method can not only provide a theoretical reference for the torsion analysis and design of such members in practical engineering, but also serve as extended teaching content for Mechanics of Materials, helping broaden students’ problem-solving thinking.