In order to solve the problem of low seismic performance of multi-story assembled steel frame energy dissipating structural connections, the study of the seismic performance of buckling restrained bracing in assembled steel frame structures based on finite element analysis is proposed. This paper puts forward the anti-buckling braced steel frame modular assembly structural system, the design requirements of anti-buckling bracing in modular structure and the structural system design method, the nonlinear finite element analysis based on the test, analyzes the structural internal force process, the internal force distribution and redistribution law, improves the internal configuration, optimizes the structural design, and establishes the pre-embedded and welded connections by using the means of indoor physical simulation. Using indoor physical simulation, two different small-scale specimens were built with pre-installed parts and welded connections to compare the hysteresis curves, skeleton curves, stiffness curves, ductility and energy dissipation parameters and other seismic performance indexes of the two structures. The experimental results show that, under the same displacement, the pre-installed specimen has greater cut-line stiffness, but the ductility coefficient is smaller; the energy dissipation coefficient and the equivalent viscous damping coefficient of the pre-installed specimen are about 0.81 times that of the welded specimen, which indicates that the buckling restraint brace has superior seismic performance by using the welded connection.