Abstract: ABAQUS 6. 10 was used to do a nonlinear numerical analysis of the four concrete filled square steel tube (CFT) frames-thin steel plate shear walls with side openings. Mechanical behavior，failure pattern and effect of side stiffening components on the stiffness，loading capacity，ductility and hysteretic behavior were researched. And the theoretical formula of cross-section selection of side stiffening components was proposed. Results obtained from this study were as follows. The concrete filled square steel tube (CFT) frames-thin steel plate shear walls with side openings had good mechanical behavior and hysteretic behavior. When the side stiffening components had hinged connections with steel girders，the side stiffening components could significantly increase the bearing capacity，stiffness，ductility and energy dissipation. The results of finite element analysis and design formula calculation were in good agreement，which provided a reference for engineering application.