▎ 摘　　要

Qualitative and quantitative studies have shown that the laser propulsion of bulk graphene sponge material (LPGS) is efficient, green and stable, which has great value in long-term flight, light-driven actuator and opticalmechanical microsystem. However, its mechanism is still in dispute due to the lack of adequate experimental evidence, hindering its applications. In this work, LPGS is comparatively studied under the high vacuum (0.002 Pa) and the rough vacuum (6 Pa). It is observed that LPGS is significant in rough vacuum but disappears in high vacuum, which experimentally refutes the propulsion mechanism based on electron ejection, and confirms that the more reasonable explanation is the laser-induced Knudsen force. This work clears the discussion about the LPGS mechanism and provides an important theoretical basis for the practical use of LPGS.