Abstract: Constitutive relations are the basis for design of composite materials. This paper summarizes the damage evolution laws, the research methodology and the major results in the study of constitutive relations of blended/filled polymeric composite materials. It is pointed out that more studies are needed to understand some important mechanisms in the damage process of the composite materials such as the nucleation and coalescence of voids, effects of the void interaction and non-linearity of the matrix on the damage evolution, effects of the strain rate and temperature on the damage process, etc.