Abstract: This paper is focused on the test results of steel beams available in the international literature and their numerical analyses of the inelastic lateral torsional instability． It was found: 1) The stability factors for welded beams were smaller than those of the rolled beams; 2) the discreteness of the test results for welded beams was larger than that of the rolled beams; 3) early test results were mainly on rolled beams，and the results were higher than more recent tests，this was because some early tests were specifically conducted to check the tangent modulus approach to inelastic buckling of initially straight beams using specially prepared specimens; later the relevant test results were decreased due to the development of dual-non-linear analysis and means; 4) the unfavorable effect of initial out-ofplane deflection was great and could not be equivalently treated by residual stresses; 5) beams with higher height-towidth ratios of the cross section had smaller stability factors; 6) loading types had a non-negligible effect on the stability factors; 7) at point of normalized slenderness ratio being equal to 1. 0; the lower limit of the stability factors was 0. 6 and 0. 5 for rolled and welded beams respectively．