Through shear test data analysis of 13 RC beams Strengthened with externally prestressed wire rope, shear failure mechanism was elaborated, and shear bearing capacity of reinforced beams were not only calculated respectively by truss -arch model and other simplified calculation methods, but also were compared with test data. Based on the result of comparation, shear capacity calculation method of RC beam Strengthed with externally prestressed wire rope was discussed. The analysis results show that the mechanism of the wire rope shear externally prestressed reinforced concrete beams against the shear is similar with stirrups inside beam. When the shear span ratio is less than 2.7, the static average ratio of the truss-arch model shear capacity caculation value and tested value is 1.02, and standard deviation statistics is 0.07. In another word, calculation value agree with experimental value. When the shear span ratio is larger than 2.7, the calculation value is bigger than test.