Abstract: In order to research on the damage mechanism of carbon/epoxy composite under the conditions of dynamic load and constant load, the experiments of the tensile damage of carbon/epoxy unidirectional composite sample on the conditions of different loading speed and constant load are done in this paper. From the damage process and AE characteristics, it is found that in the lower rate, the rupture intensity of this composite is less sensitive with the changing of tensile rate, but as the stretching rate gradually advances, the peak of matrix and interface damage appear in advance and the fracture damage gets more and more incomplete. The AE effect under constant load reflects the ability of resistance to creep, and the size of its convergence ability reflects the historical injury severity of this composite.