In this paper the authors use the hereditary theory of Boltzmann to describe the elastoviscous behavior of composites and introduce them to the dynamic mechanical analysis (DMA). In order to well describe the experimental data concerning the creep and stress relaxation in large time interval we used a sum of singular kernels in the integral hereditary s. In the linear case we have obtain the storage and loss modules as well as the loss factor as a function of the hereditary functions and kernels. One has obtained the loss factor by cycling of composites as a function of the strain amplitude and frequency. Experimental results for epoxy fiber composite with glass fibers (GFC) and natural fiber composite, namely Hemp 2.5 x 2.5 composite (HFC) [1] illustrate the applicability of the proposed approach.