By analyzing the most typical 8 components and taking the appropriate constraint condition,we can establish the finite element analysis model.Considering the influence of slenderness ratio,initial imperfection and depth-width ratio;also basing on the definition of buckling mode,we can draw a more accuracy judgment basis of buckling mode.The main conclusions are: the distortional buckling critical bearing capacity is not sensitive to slenderness ratio;the initial defect can reduce the critical buckling bearing capacity of local member;the depth-width ratio can influence the width-to-thickness ratio and the plate group effect of a section;most Flexion deformity of the components are not Ideal single,it makes essential to analyze the mechanism ofbuckling behavior;eccentricity can weaken the bearing capacity of the components,and influence the buckling mode.