Abstract: In order to investigate the effect of freeze- thaw cycles on the longitudinal wave velocity and the damage variable of saturated rock，40 freeze-thaw cycles were carried out on saturated sandstone， black cloud granulite， diorite and limestone under the condition of freezing temperature at -20 oC and melting temperature at 20 oC. The results show that the mineral composition， cementation type， pore characteristics， and the arrangement of mineral particles have a significant influence on the longitudinal wave velocity and damage variable of the rock under the same freeze-thaw conditions； after 40 freeze-thaw cycles， the longitudinal wave velocity of sandstone， black cloud granulite， diorite and limestone were decreased by 42.12%， 14.30%， 23.21% and 19.24% respectively compared with that of saturated rock samples； the reduction of longitudinal wave velocity and damage variable is more obvious in the first 5 freeze-thaw cycles. With the increase of freezing thawing times， the decreasing amplitude of the longitudinal wave velocity and the damage variable gradually decreases and tends to be stable.

Key words: Freeze- thaw cycle, Longitudinal wave velocity, Diorite, Limestone, Sandstone, Black cloud granulite