Micro Raman characterization has been used to determine the stress status of 3C-SiC epilayer grown on pseudomorphic-Si thin layer on Si_1-xGe_x/Si(001). The strain conditions of the Si_1-xGe_xfilms grown on Si(001) have been determined by the analysis of additional Silicon Raman peaks, which Raman shifts are related to the lattice parameter. Through the analysis of the Raman spectra, the correlation between the Si_1-xGe_xfilm, the crystal quality and the stress relaxation of the 3C-SiC as a function of the Germanium fraction (x), have been evaluated. The increase of Germanium fraction determines the reduction of the voids density located at the 3C-SiC/Si interface and the relaxation of the stress within the epilayer. Moreover, the 3C-SiC crystal quality, monitored by the Full Width at Half Maximum of the TO Raman mode, remains unchanged for any Germanium fraction values.