Abstract: The effect of the size of honeycomb core unit on the resistance of sandwich plate of carbon fiber reinforced polymer (CFRP) under low-velocity impact load was investigated by using the impact test system of hemisphere-head drop hammer. Based on the continuous damage mechanics model, cohesive element model and 3D Hashin damage criteria, a refined low-velocity impact simulation model for honeycomb sandwich plate with CFRP face sheets, aluminum honeycomb core and cohesive films was established in finite element simulation software ABAQUS. The simulation results are in good agreement with the experimental results. The effects of structural parameters, such as the height of honeycomb core, the thickness of face sheets and the thickness of honeycomb cell wall, on the energy absorption of honeycomb sandwich plate were further investigated by using the numerical model. The results show that increasing the cell side length of aluminum honeycomb core can reduce the stiffness of honeycomb sandwich plate and improve the energy absorption effect of sandwich plate. The core height has little effect on the stiffness and low-velocity impact resistance of the sandwich plate. Increasing the skin thickness of honeycomb sandwich board can improve the stiffness of sandwich board, but reduce the energy absorption effect of sandwich board. Increasing the cell wall thickness can improve the stiffness and low-velocity impact resistance of sandwich board.