Abstract: An unusual shaped column subjected to axial compression is located inside the casing of a large scale electrostatic precipitator. Because of the peculiarity of section and configuration of the column，its stability design round strong axis can't comply with the current structural specification. In consideration of initial geometrical imperfections and weld residual stresses，the investigation into stability round the strong axis of column by nonlinear finite element method is conducted. The research results indicate that the column doesn't present the flexural buckling round the strong axis，but presents the elasto-plastic flexural-torsional buckling. The stability increases slightly when the connecting channel shaped steel members between two limbs and the stiffeners located on connecting web are strengthened. The stability is weakened significantly when the width-thickness ratio of connecting web increases. When the slenderness of H shaped steel round the strong axis is kept constant and the height-thickness ratio of H shaped steel web increases，the stability increases. Based on a great many computation results，the evaluation recommendation is proposed for the buckling bearing capacity of column under axial compression round strong axis by numerical regression，and the design method of economical width-thickness ratio of connecting web is proposed.