Abstract: Finite element software MSC.Marc was adopted to establish finite element models for buckling restrained brace inner core with cross shaped section. The residual stress after welding was obtained, and its axial stress was analyzed in detail. Based on the intensity and distribution of the stress in the inner core at load, the influence of the welding residual stress on the inner core yield behavior was evaluated. The results show that yielding occurs first in local area near the welding line at tensile load and away from the welding line at comprssive load, in which the stress reaches yield strength due to the presence of welding residual stress. As the load increases, the inner core achieved total yield failure. So the axial tensile load and axial compressive load on the inner core are less than the designed values.