Deformation based design method is applied to the seismic evaluation of asymmetric wall systems. This paper proposed a modified capacity spectrum method using capacity curves and demand surfaces based on displacement, rotation angle and force coordinates. The proposed 3D capacity spectrum method is useful to evaluate asymmetric systems susceptible to torsional behavior. Demand surfaces represent seismic demands based on inelastic earthquake response considering twisting behavior and capacity curves represent the seismic capacity of asymmetric buildings. Using the proposed 3D capacity spectrum method, the direction of seismic retrofit strategy can be easily determined. By modifying demand surfaces or capacity curves, new performance points representing more superior performance can be found.