Abstract: Hypervelocity space debris poses a serious threat to the surfaces of on-orbit spacecraft, and impacts can cause severe damage. To ensure the safety and long-term operation of spacecraft in orbit, it is urgent to enhance their protective capabilities against such hypervelocity impacts. Numerical investigations on the impact failure behavior of metal debris against bio-inspired honeycomb sandwich structures were conducted using the finite element-smoothed particle hydrodynamics (FE-SPH) adaptive coupling method. This numerical approach converts failed finite element meshes into smoothed particle hydrodynamics particles that inherit the original physical properties of the elements, which effectively avoids energy non-conservation caused by element deletion and achieves high-fidelity reproduction of the entire impact process with large deformation and material fragmentation. First, by integrating gradient cell configurations with spiderweb-inspired topologies, a refined numerical model of a double-layer bio-inspired honeycomb sandwich panel composed of alternating layers of CFRP face sheets and honeycomb cores was established, and the reliability of the numerical model and algorithm in simulating impact damage and fragment cloud evolution was verified. Subsequently, it was demonstrated that the dual-gradient design offers significant overall advantages over conventional single-layer structures in effectively attenuating impact loads, controlling fragment cloud morphology, and improving energy absorption efficiency. Then, the dynamic damage mechanisms and failure modes of the double-layer sandwich panel under hypervelocity impact at 5818 m/s were revealed, clarifying how different cellular topologies regulate shock wave propagation paths and structural failure processes. Finally, through systematic analysis of the effects of impact velocity within the range of 2000-5000 m/s on structural mechanical response, damage evolution, fragment cloud characteristics, and energy absorption performance, it was confirmed that the double-layer spiderweb honeycomb sandwich panel exhibits optimal comprehensive protective performance. Results show that the designed bio-inspired gradient honeycomb sandwich panel significantly enhances overall protection capability under hypervelocity impact by inducing progressive layer-by-layer crushing of the core and effectively controlling fragment cloud dispersion. The findings provide important theoretical foundations and references for future lightweight impact-resistant structural designs in spacecraft.