Abstract: Lateral instability behavior of lipped H-section beams subjected to moments are investigated theoretically based on large deformation and material elastic-plasticity finite shell element analysis.Three possible failure modes will be involved in analysis,namely,plate local buckling,distortional buckling,overall buckling failure,and the interaction between them, in the case of lip's width coefficient of lipped H-section beams reaching an optimal value.The influence of both sectional geometric parameters and slenderness on lateral stability behavior of beams is analyzed systematically.Finally,based on the numbers of FEA numerical results obtained,the proposed formulas are given for predicting lateral stability capacity of lipped H-section beams under moments,which will be used in the further modification of Chinese code for steel structural design and that of engineering structures as well.