Abstract: Residual stress is one of the most important initial imperfections for the overall buckling behavior of steel compression members. An experimental investigation was carried out to quantify the residual stress in I sections welded by Q460 high strength steel , using a sectioning method. 8 section specimens with various dimensions and weld types were measured, and the magnitude and distribution of both compressive and tensile residual stresses were obtained through nearly 2000 original data. Based on the experimental results, the effects from sectional dimensions (i.e. width-thickness ratio and plate thickness), the weld type and the interaction between flanges and web were clarified. It was found that the compressive residual stress was significantly related to sectional dimension, but no clear correlation was indicated with the weld size. The tensile residual stress hardly correlated to the sectional dimension. No residual stress interaction between flanges and web was found due to the stress equilibrium within each individual plate. Besides, a distribution model was proposed, which well described the experimental results and effects from sectional dimensions.