Abstract: This paper is concerned with the damage of cross-ply carben fiber reinforcod epoxy composites under static and fatigue loading.Acoustic emission, microscopie observation,infrared thermography are employed to detect the formation and prepagation of the damage and to test the fatigue behaviour. The relationships of microstructure damage with acoustic emrssion characteristic parameter and temperatuer variation are studied.The damage mechaniesm of unnotched and notched specimens are compared.