Bio-inspired hierarchical design combined with advanced computational modelling provides an effective route for developing next-generation crashworthy structures. This study proposes bionic tree-inspired hierarchical hexagonal (BTHH) tubes and systematically investigates their crashworthiness using high-fidelity nonlinear finite element simulations under axial and oblique impact, high-velocity loading up to 80 m/s, and axial thickness gradient configurations. The results show that second-order hierarchical refinement markedly improves performance, delivering a 108% increase in specific energy absorption and a 96% increase in mean crushing force compared with conventional hexagonal tubes. An analytical model based on super folding element theory is developed to explain the hierarchical energy dissipation mechanisms and shows strong agreement with numerical predictions. The integration of numerical simulation and analytical modelling forms an efficient computational design framework, while comparison with twelve state-of-the-art bio-inspired designs confirms the superior crushing force efficiency (>80%) and robustness of the proposed BTHH tubes, demonstrating their potential for lightweight energy-absorbing applications in aerospace and automotive engineering.