Abstract: The in-plane dynamic crushing of hexagonal honeycombs with density gradients is numerically studied by using explicit dynamic finite element method. Based on the concept of functionally graded materials, the density graded honeycomb mode is firstly established. And then the effects of density gradient and impact velocity on the deformation modes and the energy absorption capacities of hexagonal honeycombs are discussed in detail. Research results show that through the proper choice of the density gradient of honeycombs, the initial stress peak could be reduced significantly, and the energy absorption could be controlled effectively. The results will provide some useful guides in the multi-objective optimization design of impact dynamic properties of cellular materials.