Abstract: Fiber reinforced polymer (FRP) bars have the characteristics of lightweight, high strength, corrosion resistance, etc., and have been widely used in various building structures to alleviate the corrosion of steel bars in the structure. Shear wall is the main lateral force-resistant component in building structures, whose seismic performance has been paid much attention. At present, only the American code ACI CODE-440.11-22 and the Canadian code CSA S806−2012 mention the design method of shear capacity of concrete shear walls reinforced with FRP bars. In this study, the effects of horizontal/vertical reinforcement ratio, shear-span ratio and axial load ratio on the shear bearing capacity of shear walls were investigated by meso-scale numerical simulation method, and the size effect on nominal shear strength of shear walls was analyzed. On the basis of the proposed formula for the shear capacity of RC shear walls based on GB 50010−2010, a calculation method for the shear capacity of concrete shear walls reinforced with FRP bars considering size effect was proposed. This calculation method can also predict the shear capacity of concrete shear walls reinforced with FRP-steel bars. The accuracy and rationality of the proposed method are verified by comparing it with the existing test results.