Abstract: The design theory of frozen soil wall is one of the core technologies for mine shaft freezing sinking. The conventional elastic design formula for the thickness of frozen soil wall has large errors when the modulus ratio of the frozen soil wall to the surrounding rock is less than 10. Considering the excavation unloading effect and the interaction between the frozen soil wall and its surrounding rock, an elastic-plastic mechanical model is established for a more rational design of the frozen soil wall. The stress and displacement analytical solutions are deduced. A new elastic-plastic formula for the thickness of the frozen soil wall is developed on the basis of the solutions. The influences of various factors on the thickness of the frozen soil wall are discussed. The analyses show that the proposed formula is more reasonable than the traditional formula of Domke, and the Coulomb-Mohr yield criterion is suggested to calculate the thickness of the frozen soil wall.