Abstract: To investigate the global buckling behaviour of welded I-section overhanging beams of Q460 high strength steel and to develop the global buckling design method for such beams in the code, six overhanging beams were totally tested under concentrated loads. The initial geometric imperfections and the residual stresses were all measured. The test results show that when the dominative stability segment of specimens is located in the simply supported span, the global buckling capacity of the specimens decreases with the increase of the overhanging’s length-to-span ratio and the height-to-width ratio of the cross section has a greater effect on the global buckling capacity of the overhanging beam than that of overhanging’s length-to-span ratio. By the grounds of the test, the finite element model considering initial geometric imperfections and residual stresses was developed. The model was validated against test results, and a good agreement was obtained. According to the validated finite element model, parametric studies were carried out to analyze the effects of the loading form, of the loading ratio, of the simply supported span length, of the overhanging length and, of the height-to-width ratio on the global buckling capacity of welded I-section overhanging beams of Q460 high strength steel. Based on the results of eigenvalue buckling analysis, the calculated formulas of elastic critical moment for the overhanging beam were obtained by regression. Furthermore, the calculated formulas of ultimate moment for the Q460 high strength steel welded I-section overhanging beam was proposed through the regression results of test and finite element parametric analysis.