Abstract: The purpose of this experiment is to investigate whether some kind of Chinese herb medicine has the effect of decreasing the morphological changes of internal organs in rabbit under simulated WL. 53 rabbits are exposed to headdown suspension to simulate the influence of WL. The rabbits are divided into four groups: contrast group, head-down suspension group, Chuan-Qipng group and Dan-Huang group (Chuan-Qiong, Dan-Huang, names of Chinese medicine). Morphological changes of the brain, lungs, heart, kidney, aorta and so-leus muscle are observed. The result showes the Chuan-Qiong (CQ) or Dan-Huang mixture (DH) has effects of improving the conditions of circulation and structure of organs in SWLrabbits, and the effect of DHseem to be better than that of CQ. So the Chinese herb medicine may have a good prospect of being used in space flight.