In this paper,8 pieces of cold-formed thin-walled steel tube beams subjected to low-cycle reversed loading were tested,and nonlinear finite element analysis were also conducted to explore the effects of span to height ratios and width to thickness ratios of cross-section on the hysteretic behavior,ductility,and the ability of energy dissipation.Some important conclusions can be extracted from the experiments and the nonlinear analysis and listed as follows:(1)The cold-formed thin-walled steel tube beams exhibited stable hysteresis behavior up to local buckling and then showed considerable good ductility and the good ability of energy dissipation.The pinch-crinkle phenomena didn't occur in the hysteresis loops of load-displacement.(2) The hysteresis behavior and ductility of cold-formed thin-walled steel tube beams depended on the span to height ratios and width to thickness ratios.(3) The proposed nonlinear FE model could accurately predict the overall seismic behavior and the inelastic performance of the cold-formed thin-walled steel tube beams.The hysteresis loops from nonlinear FE models under low-cycle reversed loading agreed well with those from the low-cyclic reversed loading tests.