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• Inspired by self-similar evolution, a novel concave-convex hierarchical honeycomb (NCHH) is proposed. • The NCHH show the characteristics of concave and convex, and the energy absorption characteristics of concave honeycomb is better than that of convex honeycomb. • Reasonable configuration of self-similarity coefficient, angle and wall thickness can effectively improve the crashworthiness of the structure under axial impact. A novel bi-directional hierarchical honeycomb is proposed. A finite element numerical model was constructed using Abaqus/Explicit, the model's accuracy was verified, and a series of in-plane impact studies were carried out. Firstly, the mechanical properties of axial impact were analyzed for different bi-directional hierarchical honeycombs. The results show that the mechanical properties of NBHH- h 1 h 2 2 h 3 -III and NBHH- h 1 h 2 h 3 h 4 -IV are the best and almost identical. Subsequently, the mechanical properties of NBHH-X h x Y h y -IIs with different layers were analyzed. Research results show that NBHH- h 3 3 h 4 -II has a 77.96 % increase in specific energy absorption (SEA) compared to NBHH- h 1 3 h 2 -II, and NBHH- h 1 3 h 2 -II has a 116.02 % increase in SEA compared to NBHH-3 h 1 h 2 -II. A parametric study of NBHHs was conducted. The mechanical properties of NBHHs with different layer ratio coefficients were analyzed, and it was found that the mechanical properties of NBHHs with l 2 = 12 and k = 0.2 are the best. Finally, the effects of wall thickness and velocity on NBHHs were analyzed. Increasing the wall thickness appropriately can effectively improve the impact resistance of the structure. Bi-directional hierarchical design provides a practical reference for enhancing the in-plane mechanical properties of honeycombs. [ABSTRACT FROM AUTHOR]