To investigate the role of E-beam treatment on the structure-properties of oxidized starch, this study investigated the influence of E-beam (1, 3, 6 kGy) pretreatment combined with NaClO oxidation (1% and 3%) on the multi-scale structural, physicochemical, and digestive properties of cassava starch. Results showed that E-beam treatment did not affect the starch surface, but the oxidative modification increased granule surface roughness. Also, the synergistic modification preserved starch growth rings, FT-IR patterns and crystal types. Further investigations revealed that E-beam induced starch molecular degradation, leading to decreased molecular weight, depolymerization of long chains, and a loss of short-range order. Moreover, oxidation treatment exacerbated the disruption in starch molecular structure, as evidenced by crystallinity loss, viscosity, and enthalpy reduction. Notably, E-beam induces starch yellowing; however, oxidative modification increases starch whiteness. Additionally, the synergistic modification improved native starch's lower solubility and enhanced the resistant starch content. Results suggest that E-beam pretreatment can enhance oxidative modification by promoting the exposure of active sites of starch molecules without destroying starch structure and can be considered an advanced, green, and efficient pretreatment for modified starch in the future.