Abstract: The influence of confining stirrups on the deformation capacity of reinforced concrete (RC) walls was studied in respects of theoretical analysis, finite element modeling (FEM) and experimental verification. From the theoretical analysis of concrete stress-strain model and the plane section assumption, adding confining stirrups has positive impacts on the deformation capacity in cases of flexural compression failure in the form of concrete crushing or bar buckling. On the other hand, in situations of flexural tension failure, adding confining stirrups has little influence on the deformation capacity. Results from both experimental studies and the Vector2 FEM validated the above conclusions. A formula was proposed to determine whether adding confining stirrups can improve the deformation capacity of a particular wall section. Predictions from the proposed formula agree very well with test results.