Steel plate shear walls with openings are highly interested because of their architectural aspects. A particular type of these systems is the steel plate shear wall with door-shaped opening; the opening is continued from the base to top beam and surrounded by boundary elements relatively weaker to main columns. Assuming the pure shear behaviour for this system, each of the side panels can be considered a steel plate shear wall with unequal VBEs (vertical boundary elements). Behaviour of this type of steel shear walls cannot be predicted by the common relations of steel shear walls; therefore, it has not been covered in technical literatures until now. In this study the behaviour of steel plate shear wall with one strong and one weak column is theoretically and numerically investigated. Theoretical relations to define the load-displacement curve were proposed. In order to study the theoretical relations comprehensively, 12 numerical models with various overall dimensions and column cross sections were investigated by finite element method; the probable errors of the results were also analysed. The obtained results show good agreement between theoretical relations and real behaviour of steel plate shear walls with unequal columns and persists the applicability of the relations in design of these systems.