The Electrical Wiring Interconnection System (EWIS) and the supporting brackets are all over the whole aircraft. In the narrow space area, considering the requirements of assembly and maintenance, it is necessary to adopt one-sided installation process in which the brackets are not easy to fixed or assembled properly during wire installation. If the brackets is not fixed properly or operated improperly, it will cause the brackets to bear the installation torque load, cause the brackets structure to produce plastic deformation and residual stress, and seriously cause the structure damage. In order to analyze the stress and deformation of typical standard EWIS bracket under installation torque, the finite element analysis of typical standard brackets is carried out by ABAQUS. Considering the nonlinear performance of materials, the deformation and stress of bracket under different installation torque are obtained. The load capacity of the bracket with plastic deformation was analyzed. The stress before and after plastic deformation is compared and analyzed, and the influence of deformation on load capacity was obtained. The paper simulates the effect of installation torque of the brackets using nonlinear finite element method, and calculates the stress level bearing inertia loads after plastic deformation, which provides a reference for the assembly process of civil aircraft EWIS bracket and the bearing analysis after plastic deformation.