Previous studies have shown that a global bending collapse hinge of thin-walled square metal tubes composed with a series of stationary hinge lines, rolling hinge lines and toroidal surfaces. In particular they have shown that the structures respond to quasi-static testing by means of an initial peak moment followed by a falling moment as deformation proceeds. This paper further studies, using finite element analysis, the bending collapse mechanism of thin-walled square metal tubes with a global hinge. Various finite element models are created with ABAQUS. Detailed numerical calculations are made in terms of the resultant moment-rotation curves, the overall collapse process, development of plastic hinge lines, profiles of the cross-section and distributions of stress and strain along the cross-section.