In this paper，we successful1y took the soft x-ray radiographs that distinctly. showed the internal damage such as microcracks in glass/epoxy composites The failure mechanisms and damage evolution law could be effectively obtained from these radiographs co-operating with AE results. Based upon the fact that the orientation of microcracks in fiber composites under loading is invariably in parallell with fiber，we define the damage variables correspond to mode Ⅰ and Ⅱ in macroscopic fracture mechanics，and obtain the constitutive equations for the damaged lamina and laminate. The calculated results coincide closely with the experimental results.