Gravel cushion is widely used for rockfall prevention in open-pit mine to absorb energy, the energy-consumption and buffer mechanism of different thickness and particle size of gravel cushion under the impact effects are studied. A series of laboratory tests for different cushion are conducted, combining the blocks' volume and drop height. The First tests under the condition of same release height of rockfall are carried out, the results indicate that under the different impact energy, the change of cushion's thickness have an obviously different effects on the coefficient of restitution (<i>COR</i>) of cushion. The second tests under the condition of same cushion thickness are conducted, when the blocks of different radius colliding with the cushion of same thickness, the <i>COR</i> change range of blocks of a big radius is larger than those blocks with a relatively small radius. For further research the influence degree of cushion's particle size and thickness on the <i>COR</i> when rockfall moving through the cushion, based on orthogonal test principle, 32 orthogonal tests are conducted, the influence law of all factors on <i>COR</i> and damage depth <i>L</i> of cushion are explored. The test results show that the cushion's thickness h should be considered firstly during the process of the cushion design, and reasonable cushion not only effectively reduce <i>COR</i>, but also maintain its stability, which provides theoretical and practical basis for the wide application of cushion design to control rockfall.