Abstract: The flexural bearing capacity of the normal section and the shear bearing capacity of the oblique section of the steel reinforced concrete (SRC) beam before and after damage were taken as the characteristic quantity, and the exponential function with the shear span ratio as the independent variable was taken as the weighting coefficient of the flexural capacity of the normal section and the shear capacity of the oblique section, and the correction coefficient related to the bending moment and shear damage rate ratio were introduced to correct the weight coefficient. The seismic damage index model of SRC beam was established, and the full damage and local damage of SRC frame beams under different shear span ratios were pre-simulated. The results show that as the shear span ratio increases, the damage degree of the component increases slightly. The damage calculated by the established model of seismic damage index of SRC beam is basically consistent with the damage characteristics of the specimens in the existing literature, and the established model can accurately characterize the damage degree of SRC beam.