Abstract: Reinforced concrete (RC) shear walls with a small shear span ratio tend to suffer brittle shear failure, and the size effect on nominal shear strength is significant. In this study, the size effect law of RC shear wall is summarized, and the calculation formula of nominal shear strength of RC shear wall considering size effect is established, which not only reflected the size effect, but also considered the quantitative influences of horizontal reinforcement ratio, of shear span ratio and of axial compression ratio. Furthermore, by introducing the coefficient α_L, a suggestion was put forward to revise the formula for the shear capacity of RC shear walls considering the size effect, thus the safety of the predicted bearing capacity of large specimens is ensured. Compared with the relevant experimental results, the results showed that the formula proposed for the shear capacity of reinforced concrete shear walls considering size effect suggested can better predict the shear capacity, and that both safety and accuracy have been improved.