Abstract: In this paper, the protective stress of honeycombs under the low and medium velocity crushing was theoretical analyzed and numerically simulated. It is found that the protective stress was periodically unloaded during the crushing process due to the reflection of the elastic wave at the supporting end. The results show that unlike the cases of the high-velocity impact, the average protective stress under the low and medium velocity crushing of the honeycombs increases with the reduction in the impact velocity. This phenomenon can be explained by the inertia effect of the micro-structures. Simply adopting the plastic collapse strength will over-evaluate the protective stress of the honeycomb under the low and medium velocity crushing. A new expression was derived to evaluate the protective stress and exhibits a good agreement with the numerical simulations.