The invention discloses a method for positioning the three-dimensional destruction shape of a tunnel curved edge wall under the horizontal earthquake force effect. According to the method, in earthquake, work applied by the earthquake is equal to energy dissipation of fracturing of surrounding rock, and based on the condition that an extreme value is calculated through a variational method, the shape function of the three-dimensional fracturing surface of the curved edge wall is determined; and by combining the boundary conditions of displacement and stress, the coefficient value of the three-dimensional fracturing surface shape function is determined, so that according to the fracturing surface shape function and the coefficient value of the fracturing surface shape function, a three-dimensional fracturing surface shape picture is drawn. The method provides a calculation method for determining the three-dimensional destruction shape of the tunnel curved edge wall under the horizontal earthquake; according to the destruction shape, reference can be provided for the reinforcement range of a curved edge wall tunnel in an earthquake area; in addition, whether the curved edge wall is safe under the earthquake or not can also be judged; and the collapse size of the curved edge wall under the earthquake is calculated. The method can also be applied to destruction range determination, reinforcement range determination, edge wall safety evaluation and the like of underground building structures, with curved edge walls, such as shield tunnels and subway section tunnels under the earthquake effect.