The horizontal stiffness of steel frame is relatively weak. So designers introduce brace system into steel frame to increase the horizontal stiffness. In order to guarantee the safety of the structure, we should imitate the performance of the structure under seismic loads. In this paper, the pseudo-dynamic test was conducted on the semi-rigid connection of steel frame and the semi-rigid connection of steel-braced frame. The test results show that the brace can increase the ductility of the structure, decrease the displacement of the top floor, decrease the interlayer displacement, and bear ground floor shearing-force. So the brace greatly impacts the performance of the structure. It has the ability of anti-earthquake and strong resistance ability of lateral force.