C/C composites have the phenomenon of the decrease of friction coefficient in wet conditions, companied with the change of wear behavior. In this paper, the effect of micro-tissue and density on the tribology behavior of C/C composites in wet conditions has been studied. The results indicate that all the above factors influence the tribology behavior of C/C composites at a different degree. It is believed that all the above factors change the ability of absorbing water by the C/C composites. The different degree of water absorption in turn changes the tribology mechanisms of C/C composites resulting in the change of tribology behavior of the C/C composites.