In this study, the scanning electron microscope was employed to examine the morphology of the inter? nal original defects and microstructure of the fiber reinforced polymer (FRP) cable. The microscopic damage model of FRP cable with internal hole and interface defects was established with ABAQUS-Python platform to analyze the multi-scale mechanical behavior of the FRP cable. The results show that the equivalent elastic modulus of the fiber is mainly affected by the porosity and the length-to-diameter ratio of the hole. Specifically, the equivalent elastic modulus increases with the reduction of the holes’cross-sectional area under the same porosity and void volume. Considering the random distribution of the holes, the simulated results of the equivalent elastic modulus of fiber are higher than those obtained by the Mori-Tanaka theoretical calculation. When the length-to-diameter ratio of the holes in the fiber is less than 1, the position of the holes has the greatest influence on the equivalent elastic modulus. Based on the shear-lag theory, the equivalent elastic modulus of the fiber linearly decreases with the interface defect rate, when considering internal interface defects of materials. Based on the random failure constitutive relation of the fiber bundle, multi-scale finite element models of cable and tendon in the macro-scale were established based on the USERMAT, and the influences of micro- and meso- scale defects on the overall performance of composite materials were investigated. Finally, the simulated results of FRP tendon and cable agreed well with the experimental results by considering various Weibull parameters and the mechanical parameters of fiber bundles with internal defects.