Abstract: The theoretical analysis method was introduced by examining the design requirements for steel plate walls or multi-cellular composite walls. Analytical theory was presented to determine the buckling factors. Based on the calculated results， the concept of threshold stiffness for edge stiffeners was identified， at which the plate buckled as a four-side supported plate. The threshold stiffness was calculated， and approximate equations were proposed. For steel plate walls and stiffeners in the elastic-plastic phase， the design approach for frames with leaning columns was introduced， where the three-side supported steel plate wall was treated as a leaning column and the edge stiffeners as the framed column， requiring the effective length of the stiffeners to be amplified to account for their bracing effect on the steel plate. A formula for the amplification factor was presented.