To explore the gusset plate buckling and its influence factors under compression caused by bracing members in braced frames,and to obtain an appropriate buckling design method,the buckling behaviors of gusset plates with varied parameters are computed by eigenvalue analysis and nonlinear analysis.With the capacity eigenvalue of elastic buckling,the effective length factor of assumed plate-column of gusset plate is derived from Euler’s formula.The influences of some key parameters on the effective length factor are studied,and a simplified bilinear formula used to calculate the effective length factor is proposed.The exact solutions of buckling capacities taking into account of the material and geometrical nonlinearities are attained by nonlinear analysis program,the buckling influence factors of the gusset plates are evaluated,and the rationality of the designed buckling capacities with the proposed effective length factors is verified.