Abstract: It is recognized that the resistance modulus of a thin-walled open-profile member can be described without determination of its cross-section’s shear center as well as the warping modulus or other parameters because the warping can be looked on as a syntheses of its slabs’ bending, and that the slabs-disassembled analyses of fictitious loads and their flexible integration can explicitly depict the complex additional effects of loads on a flexural-torsional buckled member and hence in the conclusions, embody various complex factors such as the Wagner term. In consequence, without involvement of nonlinear analysis theory of shells, the flexural- torsional buckling analysis proposed here has solved the problems of the absence of transverse loads’ Wagner term and the non-uniform additional effects of moments produced by eccentric axial loads and transverse loads in Bleich’s method. In addition, the proposal here is predicted to be widely applicable to various cross-sections, loads and constraint conditions. The method proposed in this paper has been proved to witness sound contrastive results in its application of various kinds of typical elastic flexural-torsional bucklings, especially in that of the lateral buckling of the monosymmetrical section beam characteristic of wide controversy at present. It is shown in the analysis that the traditional method, in which the thin-walled members are concentrated to their axes, would cause problems in their second-order analyses, and some other unidentifiable omissions. However, the slabs-disassembled method proposed in this paper has been proved helpful in solving such problems.