Abstract: With the extensive application of fiber reinforced composites, the study on its dynamic mechanical properties under hygrothermal environment is provided with theory research significance and practical application value. Fristly, hygrothermal treatment was performed on carbon fiber reinforced epoxy (Carbon/Epoxy) composite laminate specimen. The high strain rate compression experiment of dry/wet state specimen was performed using split hopkinson pressure bar (SHPB) technology. And the experimental results were analyzed. The results indicate that a two stages characteristic is presented in the process of dehydration/rehydration of the material, with an effect of secondary dehydration/rehydration, the strength of Carbon/Epoxy composite laminates have the strain rate sensitivity in the vertical layer direction, the strength increases nearly threefold as the strain rate increase from 1 500 s^-1 to 6 000 s^-1, with an extremely slight change of the elastic modulus. Meanwhile, hygrothermal treatment can improve the dynamic mechanical performance of this kind of material. The material after 20 d moisture absorption exhibits the highest dynamical strength, up to 12.45% growth, and the rise of dynamical strength of material by moisture absorption is more obvious when the strain rate is relatively low.