Abstract: 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.