Abstract: This paper has studied the dynamic viscoelastic spectra of PP and GFRPP material at three frequences(110,35 and 11 Hz).The results of experiment indicate that thpugh the addition of glass fibers increases the E value of PP,the.GF in PP interfere with the completeness of crystalization.While the amount of GF in PP is moderate,the dense interface layer can be formed.Under such condition,the density of materials and E is the highost.The lost energies of the interfacial layer(a'-peak) stron gly rely on the value of frequency and content of fibers which can be easily observed when dense interface layer forms;the activation energy of the a'-transformation is higher than that of Tg-trnsformation.