Steel plate shear walls are usually designed by devoting total story shear to plates and designing peripheral frames for total transferred forces from the plates to the peripheral frames. Therefore, the participation of frames in the story shear neglected conservatively. In this research, a design methodology is presented based on the real sharing of steel walls and peripheral frames in story shear. Steel walls are designed using Plate-Frame Interaction (PFI) theory for different percentages of story shear and their seismic parameters compared together by numerical modeling in nonlinear analysis software. The obtained results indicated that using the conventional design methods, devoting total story shear to the steel walls and neglecting the shear capacity of the peripheral frame could lead to the over-designed (conservative) sections. In contrast, if the seismic design of this system was performed considering the sum of the capacity of steel plate and peripheral frame and their real sharing in story shear, the system design would be efficient and economical.