The　characteristics　of　the　lateral　and　torsional　seismic　responses　of　steel　braced　concrete　frame　structures　are　studied.　It　is　revealed　that　the　dynamic　buckling　of　steel　brace　will　have　an　impact　on　the　resistance　torque　during　the　repeated　loading　process,　and　the　plastic　hinge　state　of　the　structure　will　change　imbalanced,　resulting　in　inelastic　torsion.　By　using　D＇alembert　principle,　the　mechanism　of　the　steel　braced　structure　causing　inertial　force,　inertial　torque　and　inelastic　torsional　surge　induced　by　the　brace　buckling　is　studied,　and　the　similar　performance　is　verified　by　shaking　table　test　and　finite　element　nonlinear　analysis.　The　anti-torsion　effect　of　buckling-restrained　braces　on　structures　and　the　working　mechanism　of　preventing　inelastic　torsional　burst　of　structures　are　studied.　Finally,　suggestions　are　proposed　to　use　the　ordinary　steel　braces　as　the　first　seismic　defense　line　of　CBF　concrete　frame　structures,　and　the　technical　measures　of　using　buckling-restrained　braces　to　reduce　of　inelastic　torsion　are　given.　Copyright　©2020　Engineering　Mechanics.　All　rights　reserved.