Abstract: For a wallboard in an electrostatic precipitator casing playing stressed skin effect under vertical uniform pressure on the top, the failure mode and bearing capacity were investigated by nonlinear finite element method. The influences of structural factors such as wall thickness, wall width, stiffener spacing, column brace spacing and column section size on the wallboard bearing capacity were analyzed. The results show that, shear yielding failure of the wallboard occurs when the stressed level of the column is comparatively lower. Shear yielding failure and compression yielding failure occur simultaneously when the stressed level of the column is medium. Compression yielding failure occurs when the stressed level of the column is comparatively higher. Under the equal column stressed level, the bearing capacity of the wallboard increases with the increase of wall thickness and with the decrease of wall width, stiffener spacing or column brace spacing. The bearing capacity of the wall increases as the column stiffness is increased resulting from the enlargement of column section and its stability increases.